Deposit Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deposit Contract Liabilities [Abstract]
Deposit liabilities	$ 1,551,398,000	$ 1,608,108,000
Accretion expense on deposit liabilities	$ 66,300,000	$ 51,300,000	$ 54,400,000