Global Infrastructure Fund S000001227 [Member] A C000003333 [Member] C C000003335 [Member] F C000188977 [Member] I C000003336 [Member] R C000146551 [Member] Z C000146552 [Member] MSCI World Index (net) (reflects no deduction for fees, expenses or taxes)[Member] Linked Global Infrastructure Index (net) (reflects no deduction for fees, expenses or taxes)[Member] Investment Risk [Member] Market Risk [Member] Common Stock Risk [Member] Infrastructure Companies Risk [Member] Foreign Non US and Emerging Market Securities Risk [Member] Foreign Currency and Currency Hedging Risk [Member] Master Limited Partnership Risk [Member] Preferred Securities Risk [Member] Credit and Below Investment Grade Securities Risk [Member] REIT Risk [Member] Active Management Risk [Member] Market Disruption and Geopolitical Risk [Member] Regulatory Risk [Member] Cyber Security Risk [Member] Shareholder Concentration Risk [Member] Other Investment Companies Risk [Member]