N A not applicable [Member] N R not rated [Member] BB or Lower [Member] Investments Purchased with Collateral from Securities Lending [Member] investment companies [Member] Variable Rate Senior Loan Interests [Member] C000088321 [Member] Class I C000146445 [Member] Class R6 C000088319 [Member] Class C C000088318 [Member] Class A Common Stock [Member] Corporate Bond Securities [Member] Standard & Poor's, BBB Rating [Member] Exchange Traded Funds [Member] Preferred Stock [Member] Warrant [Member] C000100148 [Member] C000100149 [Member] C000151936 [Member] C000100151 [Member] Investment Type [Axis] Net Assets Investment Company Portfolio Turnover No Trading Symbol Flag