Borrowings (Details Textuals) (USD $)	1 Months Ended	6 Months Ended
	Jul. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Borrowings (Textuals) [Abstract]
Line of Credit Facility Committed Capacity		$ 167,500,000
Outstanding letters of credit limiting undrawn capacity on secured line of credit			21,000,000
Term debt related to securitizations		410,600,000	693,500,000
Purchase price for repurchase of outstanding 3.5% and 4.0% convertible debentures	280,500,000
Convertible Debt [Member]
Borrowings (Textuals) [Abstract]
Unamortized debt discount on term debt		1,614,000	6,873,000
Senior Secured Notes due 2014 [Member]
Borrowings (Textuals) [Abstract]
Unamortized debt discount on term debt		12,700,000	14,300,000
2014 Senior Secured Notes		287,300,000	285,700,000
FHLB SF Borrowings and FRB Credit Program [Member]
Borrowings (Textuals) [Abstract]
Amortized cost of collateral pledged to Federal Reserve Bank		133,000,000	179,000,000
Fair value of collateral pledged to Federal Reserve Bank		131,900,000	188,000,000
Term debt [Member]
Borrowings (Textuals) [Abstract]
Unamortized debt discount on term debt		$ 12,800,000	$ 14,400,000
3.5% Senior Convertible Debentures due 2034 [Member]
Borrowings (Textuals) [Abstract]
Debt instrument rate		3.50%
4.0% Senior Subordinated Convertible Debentures due 2034 [Member]
Borrowings (Textuals) [Abstract]
Debt instrument rate		4.00%
7.25% Senior Subordinated Convertible Debentures due 2037 [Member]
Borrowings (Textuals) [Abstract]
First put dates of Convertible Debentures amortized		7/15/2012
Debt instrument rate		7.25%