Debt (Narrative) (Details) (USD $)	12 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended								12 Months Ended	0 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended
	Dec. 31, 2012 entity	Dec. 31, 2011	Dec. 31, 2012 Warehouse Facilities [Member]	Mar. 31, 2012 Revolving Secured Line Of Credit [Member]	Dec. 31, 2012 Revolving Secured Line Of Credit [Member]	Dec. 31, 2012 Warehouse Facility II [Member]		Dec. 31, 2012 Warehouse Facility III [Member]		Dec. 31, 2012 Warehouse Facility IV [Member]		Dec. 31, 2012 Warehouse Facility III And IV [Member]	Dec. 31, 2012 Senior Notes [Member]	Mar. 03, 2011 $100.0 Million Senior Notes [Member]	Dec. 31, 2012 $100.0 Million Senior Notes [Member]		Feb. 01, 2010 $250.0 Million Senior Notes [Member]	Dec. 31, 2012 $250.0 Million Senior Notes [Member]		Dec. 31, 2012 Mortgage Note [Member]	Dec. 31, 2009 Mortgage Note [Member]	Dec. 31, 2008 Mortgage Note [Member]	Dec. 31, 2012 LIBOR [Member] Revolving Secured Line Of Credit [Member]	Mar. 31, 2012 LIBOR [Member] Revolving Secured Line Of Credit [Member]	Dec. 31, 2012 Prime Rate [Member] Revolving Secured Line Of Credit [Member]	Mar. 31, 2012 Prime Rate [Member] Revolving Secured Line Of Credit [Member]	Dec. 31, 2012 Commercial Paper Rate [Member] Warehouse Facility II [Member]	Sep. 30, 2012 Commercial Paper Rate [Member] Warehouse Facility II [Member]	Dec. 31, 2012 6.75% Cap Interest Rate [Member] Warehouse Facility II [Member]		Dec. 31, 2011 6.75% Cap Interest Rate [Member] Warehouse Facility II [Member]		Dec. 31, 2012 6.75% Cap Interest Rate [Member] Warehouse Facility III [Member]		Dec. 31, 2011 6.75% Cap Interest Rate [Member] Warehouse Facility III [Member]		Dec. 31, 2012 5.00% Cap Interest Rate [Member] Warehouse Facility III [Member]		Dec. 31, 2012 5.5% Cap Interest Rate [Member] Warehouse Facility IV [Member]		Dec. 31, 2011 5.5% Cap Interest Rate [Member] Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Line of credit facility				$ 205,000,000	$ 235,000,000
Maturity Date				Jun. 22, 2014	Jun. 22, 2015
Debt financing amount			475,000,000			325,000,000	[1]	75,000,000	[1]	75,000,000	[1]	75,000,000	350,000,000	100,000,000			250,000,000												325,000,000		325,000,000		75,000,000		75,000,000		75,000,000		75,000,000		75,000,000
Percentage of net book value of loans			80.00%		80.00%
Maximum hedging reserve					1,000,000
Cap Interest Rate																													6.75%	[2]	6.75%	[2]	6.75%	[2]	6.75%	[2]	5.00%	[2]	5.50%	[2]	5.50%	[2]
Percentage of collections on contributed loans			6.00%
Senior notes stated interest rate													9.125%							5.70%		5.35%
Debt maturity date						Dec. 27, 2015	[1],[3]	Sep. 10, 2015	[1],[4]	Feb. 19, 2014	[1],[3]		Feb. 01, 2017							Jun. 22, 2014	Jun. 09, 2009
Close date, secured financings						Dec. 27, 2012	[1]	Jun. 29, 2012	[1]	Aug. 19, 2011	[1]				Mar. 03, 2011	[5]		Feb. 01, 2010	[5]
Percentage of price for senior notes issued														106.00%			97.495%
Gross proceeds														106,000,000			243,700,000
Senior notes yield to maturity														7.83%			9.625%
Debt covenants	1
Basis spread on variable rate																							1.875%	2.25%	0.875%	1.25%	2.00%	2.75%
Mortgage note	$ 4,000,000	$ 4,300,000
Number of wholly-owned subsidiaries	5
Monthly servicing fee per financing	6.00%

[1] Financing made available only to a specified subsidiary of the Company.

[2] Rate excludes the spread over the LIBOR rate or the commercial paper rate, as applicable.

[3] Represents the revolving maturity date. The outstanding balance will amortize after the maturity date based on the cash flows of the pledged assets.

[4] Represents the revolving maturity date. The outstanding balance will amortize after the revolving maturity date and any amounts remaining on September 10, 2017 will be due.

[5] The close dates associated with the issuance of $250.0 million and $100.0 million of the Senior Notes were on February 1, 2010 and March 3, 2011, respectively.