Debt Obligations - Repurchase Obligations Outstanding (Parenthetical) (Detail) (Repurchase Agreements [Member]) In Millions, unless otherwise specified						3 Months Ended
	Mar. 31, 2014 Revolving Repurchase Facilities [Member] JP Morgan [Member] USD ($)	Mar. 31, 2014 Revolving Repurchase Facilities [Member] JP Morgan [Member] GBP (£)	Mar. 31, 2014 Revolving Repurchase Facilities [Member] Maximum [Member] JP Morgan [Member] USD ($)	Mar. 31, 2014 Revolving Repurchase Facilities [Member] Maximum [Member] Morgan Stanley [Member] USD ($)	Mar. 31, 2014 Revolving Repurchase Facilities [Member] Maximum [Member] Morgan Stanley [Member] GBP (£)	Mar. 31, 2014 Asset-Specific Repurchase Agreements [Member] JP Morgan [Member] USD ($)	Mar. 31, 2014 Asset-Specific Repurchase Agreements [Member] Wells Fargo [Member] Agreement
Line of Credit Facility [Line Items]
Facility size	$ 252.5	£ 153.0	$ 250.0	$ 412.6	£ 250.0	$ 71.6
Repurchase Date						Jun. 27, 2014
Number of asset-specific repurchase agreements							3