Loan Securitization/Sale Activities (Details) (USD $)	3 Months Ended				12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011 loan Y	Dec. 31, 2011	Dec. 31, 2010 loan Y
Loan Securitization/Sale Activities
Effective cost of funds (as a percent)						3.50%
Number of mortgage loans separated						5
Aggregate face value of mortgage loans separated						$ 178,000,000
Number of separated senior loans contributed to securitization trust						5
Face value of contributed loans						84,000,000
Proceeds from securitization of contributed loans		69,700,000		56,000,000		92,000,000
Proceeds from sale of loan to independent third party			78,400,000
Amount of junior loans retained						94,000,000
Remaining maturity of contributed loans, low end of range (in years)						4
Remaining maturity of contributed loans, high end of range (in years)						7
Number of loans out of first mortgage loans split into A Note and B Note						2
Number of loans out of first mortgage loans split into A Note, B Note and C Note						3
Number of contributed loans not qualifying for sale treatment						2
Balance of loans pledged to the securitization trust	50,316,000				50,316,000	50,297,000
Related liability of the securitization trust	53,199,000				53,199,000	54,086,000
Number of loans contributed to securitization trust				3
Gain on the sale of loan qualifying for sales treatment		5,100,000		1,900,000
Gain on sale of loan to independent third party			3,400,000		10,314,000	9,253,000
Net gain on the sale of loan qualifying for sales treatment				1,800,000
Net gain on sale of loan to independent third party			2,900,000
Realized losses on interest rate hedges terminated in connection with the loans being sold		7,400,000	500,000	100,000
Carrying value of loans sold into a securitization	42,500,000	154,400,000
Realized gains on the credit hedges that was terminated in connection with the loans being sold		$ 2,200,000