Subsequent Events (Details) (USD $)	12 Months Ended		1 Months Ended				1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 28, 2013 Subsequent Event [Member]	Dec. 31, 2012 RBS Warehouse Facility [Member]		Dec. 31, 2011 RBS Warehouse Facility [Member]	Mar. 31, 2013 RBS Warehouse Facility [Member] Subsequent Event [Member]	Dec. 31, 2012 LIBOR [Member] RBS Warehouse Facility [Member]	Mar. 31, 2013 LIBOR [Member] RBS Warehouse Facility [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Facility Amount	$ 425,000,000	$ 550,000,000		$ 125,000,000	[1]	$ 125,000,000	$ 125,000,000
Debt Instrument, Basis Spread on Variable Rate								1.40%	2.25%
Advance Rate				53.00%	[1]	53.00%	65.00%
Term-out feature							1 year
Dividends approved for fourth quarter	$ 51,200,000	$ 51,800,000	$ 4,900,000

[1] Facility was renewed in March 2013. See Note 16 - Subsequent Events for information on renewal of this facility.