Investments [Domain] C000015528 [Member] C000015528 C000087985 [Member] C000087985 S&P National AMT-Free Municipal Bond [Member] S&P National AMT-Free Municipal Bond Warrants [Member] Warrants C000189669 [Member] C000189669 C000015524 [Member] C000015524 S&P Intermediate Term California AMT-Free Municipal Bond [Member] S&P Intermediate Term California AMT-Free Municipal Bond U.S. Treasury Securities [Member] U.S. Treasury Securities C000015521 [Member] C000015521 S&P Municipal California 50% Investment Grade Bond/50% High Yield Bond (Inception Date 4/10/2017) [Member] S&P Municipal California 50% Investment Grade Bond/50% High Yield Bond (Inception Date 4/10/2017) C000189670 [Member] C000189670 S&P Intermediate Term California AMT-Free Municipal Bond (Inception Date 4/10/2017) [Member] S&P Intermediate Term California AMT-Free Municipal Bond (Inception Date 4/10/2017) C000087984 [Member] C000087984 C000087986 [Member] C000087986 S&P National AMT-Free Municipal Bond (Inception Date 4/10/2017) [Member] S&P National AMT-Free Municipal Bond (Inception Date 4/10/2017) Other Assets and Liabilities [Member] Other Assets and Liabilities S&P Municipal California 50% Investment Grade Bond/50% High Yield Bond [Member] S&P Municipal California 50% Investment Grade Bond/50% High Yield Bond C000087987 [Member] C000087987 C000015522 [Member] C000015522 Affiliated Funds [Member] Affiliated Funds Municipal Securities [Member] Municipal Securities C000015525 [Member] C000015525 Net Assets Investment Company, Portfolio Turnover Investment Type [Axis]