v3.26.1
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 60 Months Ended 120 Months Ended
May 31, 2026
May 31, 2026
May 31, 2026
C000021763 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Asset Allocation Fund    
Average Annual Return, Percent 15.10% 7.55% 7.90%
C000021764 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Equities Index Fund    
Average Annual Return, Percent 22.40% 8.27% 8.88%
C000021765 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Government Bond Fund    
Average Annual Return, Percent 4.75% (1.37%) 0.98%
C000021766 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Growth Fund    
Average Annual Return, Percent 3.59% 0.07% 8.63%
C000021768 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Large Cap Core Fund    
Average Annual Return, Percent 20.29% 9.78% 14.66%
C000021769 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Mid Cap Index Fund    
Average Annual Return, Percent 25.52% 7.65% 10.91%
C000021770 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Mid Cap Strategic Growth Fund    
Average Annual Return, Percent 19.00% 8.37% 14.21%
C000021772 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Nasdaq-100® Index Fund    
Average Annual Return, Percent 42.49% 17.59% 21.41%
C000021773 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Science & Technology Fund    
Average Annual Return, Percent 60.51% 16.89% 22.26%
C000021774 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Systematic Growth Fund    
Average Annual Return, Percent 26.47% 10.36% 15.93%
C000021776 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Small Cap Index Fund    
Average Annual Return, Percent 42.62% 6.21% 10.84%
C000021777 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Socially Responsible Fund    
Average Annual Return, Percent 21.53% 7.72% 9.85%
C000021778 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Stock Index Fund    
Average Annual Return, Percent 29.47% 13.80% 15.28%
C000021782 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Government Securities Fund    
Average Annual Return, Percent 4.23% (0.02%) 1.13%
C000021783 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Systematic Core Fund    
Average Annual Return, Percent 22.73% 11.24% 14.31%
C000021785 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Dividend Value Fund    
Average Annual Return, Percent 21.89% 9.75% 10.71%
C000021786 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Inflation Protected Fund    
Average Annual Return, Percent 5.80% 1.44% 2.74%
C000022843 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Systematic Value Fund    
Average Annual Return, Percent 25.53% 11.53% 11.35%
C000022844 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Value Fund    
Average Annual Return, Percent 28.45% 9.87% 8.89%
C000022845 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Emerging Economies Fund    
Average Annual Return, Percent 54.26% 7.42% 10.53%
C000022846 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Global Strategy Fund    
Average Annual Return, Percent 26.24% 8.00% 7.01%
C000022849 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Small Cap Core Fund    
Average Annual Return, Percent 17.83% 3.80% 8.52%
C000022851 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Growth Fund    
Average Annual Return, Percent 28.81% 13.09% 16.99%
C000059956 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Global Real Estate Fund    
Average Annual Return, Percent 11.35% 1.04% 3.86%
C000121199 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Dynamic Allocation Fund    
Average Annual Return, Percent 16.62% 5.77% 7.97%
C000222575 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Aggressive Allocation Lifestyle Fund    
Average Annual Return, Percent 21.58% 8.09% 9.94%
C000222576 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name U.S. Socially Responsible Fund    
Average Annual Return, Percent 24.86% 11.81% 14.00%
C000222577 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Capital Appreciation Fund    
Average Annual Return, Percent 25.21% 14.10% 16.08%
C000222578 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Conservative Allocation Lifestyle Fund    
Average Annual Return, Percent 13.07% 4.11% 5.92%
C000222579 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Core Bond Fund    
Average Annual Return, Percent 5.58% 0.28% 2.05%
C000222580 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name High Yield Bond Fund    
Average Annual Return, Percent 8.53% 4.20% 5.49%
C000222581 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name International Opportunities Fund    
Average Annual Return, Percent 18.79% 3.13% 7.33%
C000222582 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Mid Cap Value Fund    
Average Annual Return, Percent 20.29% 8.01% 9.92%
C000222583 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Moderate Allocation Lifestyle Fund    
Average Annual Return, Percent 17.39% 6.44% 8.40%
C000222584 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Small Cap Value Fund    
Average Annual Return, Percent 42.14% 7.34% 9.63%
C000224903 [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Small Cap Growth Fund    
Average Annual Return, Percent 25.99% 0.37% 12.76%
Bloomberg Global Aggregate Index USD hedged [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg Global Aggregate Index (USD hedged)    
Average Annual Return, Percent 3.77% 0.90% 2.08%
Russell 3000 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 3000® Index    
Average Annual Return, Percent 29.45% 12.92% 15.12%
Standard & Poor's 500 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name S&P 500® Index    
Average Annual Return, Percent 29.78% 14.15% 15.65%
MSCI EAFE Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI EAFE Index (net)    
Average Annual Return, Percent 22.80% 8.79% 9.28%
Russell 1000 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 1000® Index    
Average Annual Return, Percent 28.85% 13.33% 15.38%
MSCI ACWI ex USA Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI ACWI ex USA Index (net)    
Average Annual Return, Percent 32.77% 8.77% 9.82%
MSCI ACWI Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI ACWI Index (net)    
Average Annual Return, Percent 30.27% 11.45% 12.81%
Bloomberg U S Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent 5.13% 0.17% 1.70%
Bloomberg U S Universal Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg U.S. Universal Index    
Average Annual Return, Percent 5.50% 0.54% 2.10%
Sixty S And P 500 Index 40 Bloomberg U S Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 60% S&P 500® Index; 40% Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent 19.53% 8.57% 10.13%
Seventy FTSE WGBI Index unhedged 30 JPMorgan EMBI Global Diversified Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 70% FTSE WGBI Index (unhedged); 30% JPMorgan EMBI Global Diversified Index    
Average Annual Return, Percent 5.76% (1.12%) 1.17%
S And P MidCap 400 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name S&P MidCap 400® Index    
Average Annual Return, Percent 25.88% 8.08% 11.30%
Russell Midcap Growth Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell Midcap® Growth Index    
Average Annual Return, Percent 7.88% 6.86% 12.74%
Nasdaq 100 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Nasdaq-100® Index    
Average Annual Return, Percent 43.09% 18.17% 22.06%
S And P North American Technology Sector Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name S&P North American Technology Sector Index    
Average Annual Return, Percent 66.24% 22.27% 25.47%
Russell 1000 Growth Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 1000® Growth Index    
Average Annual Return, Percent 28.66% 15.73% 18.86%
Russell 2000 Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 2000® Index    
Average Annual Return, Percent 43.08% 6.61% 11.21%
Bloomberg U S Government Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg U.S. Government Bond Index    
Average Annual Return, Percent 3.71% (0.31%) 1.08%
Russell 1000 Value Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 1000® Value Index    
Average Annual Return, Percent 28.55% 10.42% 11.37%
Bloomberg U S TIPS Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg U.S. TIPS Index    
Average Annual Return, Percent 4.90% 1.23% 2.84%
MSCI EAFE Value Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI EAFE Value Index (net)    
Average Annual Return, Percent 30.07% 12.78% 9.97%
MSCI Emerging Markets Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI Emerging Markets Index (net)    
Average Annual Return, Percent 54.31% 7.54% 10.66%
Sixty MSCI ACWI Index net 40 Bloomberg Global Aggregate Index USD hedged [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 60% MSCI ACWI Index (net); 40% Bloomberg Global Aggregate Index (USD hedged)    
Average Annual Return, Percent 19.19% 7.30% 8.63%
Russell 2000 Value Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 2000® Value Index    
Average Annual Return, Percent 44.36% 7.27% 10.50%
FTSE EPRA NAREIT Developed Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name FTSE EPRA /NAREIT Developed Index (net)    
Average Annual Return, Percent 13.28% 1.68% 3.60%
Fifty Six Russell 3000 Index 19 MSCI EAFE Index net 25 Bloomberg U S Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 56% Russell 3000® Index; 19% MSCI EAFE Index (net); 25% Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent 21.93% 9.05% 10.78%
Twenty Six Russell 3000 Index 9 MSCI EAFE Index net 65 Bloomberg U S Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 26% Russell 3000® Index; 9% MSCI EAFE Index (net); 65% Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent 12.77% 4.33% 5.98%
FTSE US High Yield Market Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name FTSE US High-Yield Market Index    
Average Annual Return, Percent 7.44% 4.51% 5.82%
MSCI ACWI ex USA SMID Cap Index net [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name MSCI ACWI ex USA SMID Cap Index (net)    
Average Annual Return, Percent 29.74% 7.17% 8.94%
Russell Midcap Value Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell Midcap® Value Index    
Average Annual Return, Percent 27.21% 8.57% 10.40%
Forty One Russell 3000 Index 14 MSCI EAFE Index net 45 Bloomberg U S Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name 41% Russell 3000® Index; 14% MSCI EAFE Index (net); 45% Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent 17.29% 6.69% 8.39%
Russell 2000 Growth Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Russell 2000® Growth Index    
Average Annual Return, Percent 41.87% 5.80% 11.53%