S&P 500 (Inception Date 4/10/17) [Member] S&P 500 (Inception Date 4/10/17) Russell 3000 (Inception Date 4/10/17) [Member] Russell 3000 (Inception Date 4/10/17) C000016484 [Member] C000016484 C000016468 [Member] C000016468 UNITED STATES C000016464 [Member] C000016464 C000016474 [Member] C000016474 MSCI World [Member] MSCI World C000016471 [Member] C000016471 C000055503 [Member] C000055503 SOUTH AFRICA C000189760 [Member] C000189760 Russell 1000 Growth (Inception Date 4/10/17) [Member] Russell 1000 Growth (Inception Date 4/10/17) Technology Hardware, Storage and Peripherals [Member] Technology Hardware, Storage and Peripherals C000016470 [Member] C000016470 C000055506 [Member] C000055506 C000088007 [Member] C000088007 Semiconductors and Semiconductor Equipment [Member] Semiconductors and Semiconductor Equipment C000016477 [Member] C000016477 Water Utilities [Member] Water Utilities C000016473 [Member] C000016473 Russell 3000 [Member] Russell 3000 C000016488 [Member] C000016488 Banks [Member] Banks C000189764 [Member] C000189764 C000016462 [Member] C000016462 S&P 500 [Member] S&P 500 Software [Member] Software C000016465 [Member] C000016465 Russell 1000 Value (Inception Date 4/10/17) [Member] Russell 1000 Value (Inception Date 4/10/17) Electric Utilities [Member] Electric Utilities C000189761 [Member] C000189761 Russell 2000 (Inception Date 4/10/17) [Member] Russell 2000 (Inception Date 4/10/17) Biotechnology [Member] Biotechnology C000016485 [Member] C000016485 Russell 1000 Value [Member] Russell 1000 Value Independent Power Producers and Energy Traders [Member] Independent Power Producers and Energy Traders Common Stock [Member] Investments [Domain] C000016476 [Member] C000016476 C000016466 [Member] C000016466 C000189759 [Member] C000189759 C000016486 [Member] C000016486 S&P 500 Utilities [Member] S&P 500 Utilities Russell 1000 Growth [Member] Russell 1000 Growth CANADA C000055505 [Member] C000055505 NYSE Arca Gold Miners [Member] NYSE Arca Gold Miners Multi-Utilities [Member] Multi-Utilities UNITED KINGDOM C000016463 [Member] C000016463 Pharmaceuticals [Member] Pharmaceuticals C000016469 [Member] C000016469 Interactive Media and Services [Member] Interactive Media and Services Other Assets and Liabilities [Member] Other Assets and Liabilities Russell 2000 [Member] Russell 2000 C000055501 [Member] C000055501 Russell 1000 [Member] Russell 1000 C000189758 [Member] C000189758 AUSTRALIA C000016487 [Member] C000016487 Electrical Equipment [Member] Electrical Equipment Russell 1000 (Inception Date 4/10/17) [Member] Russell 1000 (Inception Date 4/10/17) C000016467 [Member] C000016467 Rights [Member] Gas Utilities [Member] Gas Utilities Short-Term Investment [Member] Short-Term Investment C000016472 [Member] C000016472 Construction and Engineering [Member] Construction and Engineering C000016475 [Member] C000016475 Consumer Staples Distribution & Retail [Member] Consumer Staples Distribution & Retail Net Assets Investment Company, Portfolio Turnover Investment Type [Axis]