Schedule of Investments - Future Contracts (Parenthetical) In Millions, unless otherwise specified	3 Months Ended						12 Months Ended						3 Months Ended				12 Months Ended
	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 66.0 Million Australian Dollar Vs. USD 60.8 Million For Settlement June 16, 2014 [Member] USD ($)	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 66.0 Million Australian Dollar Vs. USD 60.8 Million For Settlement June 16, 2014 [Member] AUD	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 356.0 Million Norwegian Krone Vs. USD 59.3 Million For Settlement June 16, 2014 [Member] USD ($)	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 356.0 Million Norwegian Krone Vs. USD 59.3 Million For Settlement June 16, 2014 [Member] NOK	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 69.9 Million New Zealand Dollars Vs. USD 60.2 Million For Settlement June 16, 2014 [Member] USD ($)	Mar. 31, 2014 Currency Futures Contracts Purchased [Member] 69.9 Million New Zealand Dollars Vs. USD 60.2 Million For Settlement June 16, 2014 [Member] NZD	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 73.3 Million Australian Dollar vs. USD 65.5 Million For Settlement March 17, 2014 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 73.3 Million Australian Dollar vs. USD 65.5 Million For Settlement March 17, 2014 [Member] AUD	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 406.0 Million Norwegian Krone vs. USD 66.7 Million For Settlement March 17, 2014 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 406.0 Million Norwegian Krone vs. USD 66.7 Million For Settlement March 17, 2014 [Member] NOK	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 79.5 Million New Zealand Dollars vs. USD 65.0 Million For Settlement March 17, 2014 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Purchased [Member] 79.5 Million New Zealand Dollars vs. USD 65.0 Million For Settlement March 17, 2014 [Member] NZD	Mar. 31, 2014 Currency Futures Contracts Sold [Member] 6,000 Million Japanese Yen Vs. USD 58.3 Million For June 16, 2014 [Member] USD ($)	Mar. 31, 2014 Currency Futures Contracts Sold [Member] 6,000 Million Japanese Yen Vs. USD 58.3 Million For June 16, 2014 [Member] JPY (¥)	Mar. 31, 2014 Currency Futures Contracts Sold [Member] 51.6 Million Swiss Francs Vs. USD 58.5 Million For Settlement June 16, 2014 [Member] USD ($)	Mar. 31, 2014 Currency Futures Contracts Sold [Member] 51.6 Million Swiss Francs Vs. USD 58.5 Million For Settlement June 16, 2014 [Member] CHF	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 47.5 Million Euro vs. USD 65.5 Million For Settlement March 17, 2017 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 47.5 Million Euro vs. USD 65.5 Million For Settlement March 17, 2017 [Member] EUR (€)	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 6,725 Million Japanese Yen vs. USD 64.0 Million For Settlement March 17, 2014 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 6,725 Million Japanese Yen vs. USD 64.0 Million For Settlement March 17, 2014 [Member] JPY (¥)	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 58.0 Million Swiss Francs vs. USD 65.3 Million For Settlement March 17, 2014 [Member] USD ($)	Dec. 31, 2013 Currency Futures Contracts Sold [Member] 58.0 Million Swiss Francs vs. USD 65.3 Million For Settlement March 17, 2014 [Member] CHF
Schedule of Investments [Line Items]
Forward contract indexed to issuer's equity, settlement date or dates	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Jun. 16, 2014	Mar. 17, 2017	Mar. 17, 2017	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014	Mar. 17, 2014
Hedged currency		66.0		356.0		69.9		73.3		406.0		79.5		¥ 6,000.0		51.6		€ 47.5		¥ 6,725.0		58.0
Base currency	$ 60.8		$ 59.3		$ 60.2		$ 65.5		$ 66.7		$ 65.0		$ 58.3		$ 58.5		$ 65.5		$ 64.0		$ 65.3