Related Party Transactions (Details) (USD $)	0 Months Ended
	Mar. 01, 2013 lender	Mar. 31, 2013	Feb. 28, 2013
Line of Credit Facility [Line Items]
Maximum capacity under credit facility		$ 750,000,000.0	$ 550,000,000.0
Bank of New York Mellon Corporation | New credit facility
Line of Credit Facility [Line Items]
Maximum capacity under credit facility	750,000,000.0
Number of lenders	13
Line of credit facility, committed	$ 60,000,000.0