Debt - Additional Information (Detail) (USD $)	6 Months Ended			18 Months Ended
	Jun. 30, 2013 Master Repurchase Agreements [Member]	Jun. 30, 2013 Master Repurchase Agreements [Member] Minimum [Member]	Jun. 30, 2013 Master Repurchase Agreements [Member] Maximum [Member]	Jun. 30, 2013 Term Loan [Member]	Jun. 06, 2013 Term Loan [Member] Second Incremental Loan [Member]
Schedule Of Debt [Line Items]
Second Incremental Secured Credit Facility				$ 825,000,000	$ 200,000,000
Deferred debt issuance costs				5,300,000
General and administrative expenses				4,700,000
Outstanding line of credit facility	2,400,000,000
Interest rate spread		2.25%	3.50%
Lines of credit, term	The interest rates on the facilities are primarily based on LIBOR plus between 2.25% and 3.50%
Maturity/Expiration	May 31, 2014
Residential loans pledged as collateral	$ 1,800,000,000