v3.26.1
Shareholder Report, Holdings (Details)
Apr. 30, 2026
C000006707 [Member] | Fitch, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000006707 [Member] | Fitch, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000006707 [Member] | Fitch, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40%
C000006707 [Member] | Fitch, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006707 [Member] | Fitch, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70%
C000006707 [Member] | Fitch, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.30%
C000006707 [Member] | Fitch, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.50%
C000006707 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000006707 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70%
C000006707 [Member] | Moody's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006707 [Member] | Money Market Funds Quality [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006707 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006707 [Member] | US Government Debt Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50%
C000006707 [Member] | Fixed Income Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.20%
C000006707 [Member] | Federal Agencies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006708 [Member] | Fitch, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000006708 [Member] | Fitch, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000006708 [Member] | Fitch, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40%
C000006708 [Member] | Fitch, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006708 [Member] | Fitch, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70%
C000006708 [Member] | Fitch, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.30%
C000006708 [Member] | Fitch, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.50%
C000006708 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000006708 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70%
C000006708 [Member] | Moody's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006708 [Member] | Money Market Funds Quality [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006708 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006708 [Member] | US Government Debt Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50%
C000006708 [Member] | Fixed Income Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.20%
C000006708 [Member] | Federal Agencies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006709 [Member] | Fitch, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000006709 [Member] | Fitch, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000006709 [Member] | Fitch, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40%
C000006709 [Member] | Fitch, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006709 [Member] | Fitch, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70%
C000006709 [Member] | Fitch, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.30%
C000006709 [Member] | Fitch, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.50%
C000006709 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000006709 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70%
C000006709 [Member] | Moody's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006709 [Member] | Money Market Funds Quality [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006709 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006709 [Member] | US Government Debt Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50%
C000006709 [Member] | Fixed Income Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.20%
C000006709 [Member] | Federal Agencies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006710 [Member] | Fitch, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000006710 [Member] | Fitch, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000006710 [Member] | Fitch, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40%
C000006710 [Member] | Fitch, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006710 [Member] | Fitch, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70%
C000006710 [Member] | Fitch, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.30%
C000006710 [Member] | Fitch, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.50%
C000006710 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000006710 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70%
C000006710 [Member] | Moody's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000006710 [Member] | Money Market Funds Quality [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006710 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000006710 [Member] | US Government Debt Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50%
C000006710 [Member] | Fixed Income Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.20%
C000006710 [Member] | Federal Agencies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000200511 [Member] | Fitch, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000200511 [Member] | Fitch, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000200511 [Member] | Fitch, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40%
C000200511 [Member] | Fitch, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000200511 [Member] | Fitch, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.70%
C000200511 [Member] | Fitch, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.30%
C000200511 [Member] | Fitch, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.50%
C000200511 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000200511 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70%
C000200511 [Member] | Moody's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000200511 [Member] | Money Market Funds Quality [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000200511 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000200511 [Member] | US Government Debt Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50%
C000200511 [Member] | Fixed Income Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.20%
C000200511 [Member] | Federal Agencies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000126358 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000126358 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000126358 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000126358 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000126358 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000126358 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000126358 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000126358 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000126358 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000126358 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000126358 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000126358 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000126358 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000126358 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000126358 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000126358 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000126358 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000126358 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000126358 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000126358 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000126358 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000126358 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006698 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006698 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006698 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006698 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006698 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006698 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006698 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006698 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006698 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006698 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006698 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006698 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006698 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006698 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006698 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006698 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006698 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006698 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006698 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006698 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006698 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006698 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006705 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006705 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006705 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006705 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006705 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006705 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006705 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006705 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006705 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006705 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006705 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006705 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006705 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006705 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006705 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006705 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006705 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006705 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006705 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006705 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006705 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006705 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006706 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006706 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006706 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006706 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006706 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006706 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006706 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006706 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006706 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006706 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006706 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006706 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006706 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006706 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006706 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006706 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006706 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006706 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006706 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006706 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006706 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006706 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006699 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006699 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006699 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006699 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006699 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006699 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006699 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006699 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006699 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006699 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006699 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006699 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006699 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006699 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006699 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006699 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006699 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006699 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006699 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006699 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006699 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006699 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006700 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006700 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006700 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006700 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006700 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006700 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006700 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006700 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006700 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006700 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006700 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006700 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006700 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006700 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006700 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006700 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006700 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006700 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006700 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006700 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006700 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006700 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006701 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006701 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006701 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006701 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006701 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006701 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006701 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006701 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006701 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006701 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006701 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006701 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006701 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006701 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006701 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006701 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006701 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006701 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006701 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006701 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006701 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006701 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006703 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006703 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006703 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006703 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006703 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006703 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006703 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006703 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006703 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006703 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006703 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006703 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006703 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006703 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006703 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006703 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006703 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006703 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006703 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006703 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006703 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006703 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%
C000006697 [Member] | NVIDIA Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006697 [Member] | Microsoft Corp [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90%
C000006697 [Member] | Visa Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000006697 [Member] | Amazon com Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.70%
C000006697 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006697 [Member] | Alphabet Inc A [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000006697 [Member] | Apple Inc [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60%
C000006697 [Member] | Tencent Holdings Ltd [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50%
C000006697 [Member] | Schneider Electric SE [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006697 [Member] | L Oreal S A [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000006697 [Member] | Other Countries [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006697 [Member] | INDIA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006697 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 5.10%
C000006697 [Member] | SWITZERLAND  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000006697 [Member] | TAIWAN  
Holdings [Line Items]  
Percent of Total Investments 6.60%
C000006697 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 2.20%
C000006697 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 68.60%
C000006697 [Member] | CHINA  
Holdings [Line Items]  
Percent of Total Investments 4.50%
C000006697 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000006697 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000006697 [Member] | Money Market Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000006697 [Member] | Equity [Member]  
Holdings [Line Items]  
Percent of Total Investments 98.60%