Derivative Instruments (Details) - Schedule of settlement of fair value hedges (USD $) In Thousands, unless otherwise specified	9 Months Ended		1 Months Ended	9 Months Ended
	Sep. 30, 2012 Notes Payable And Debt [Member] Fair Value Hedging Member	Sep. 30, 2011 Notes Payable And Debt [Member] Fair Value Hedging Member	Jul. 31, 2012 Deposit Liabilities [Member]	Sep. 30, 2012 Deposit Liabilities [Member] Fair Value Hedging Member	Sep. 30, 2011 Deposit Liabilities [Member] Fair Value Hedging Member
Derivative [Line Items]
Cumulative reduction to interest expense	$ 13,973	$ 9,173		$ 17,060	$ 7,511
Fair Value Hedge Remaining Balance	$ 7,651	$ 12,451		$ 216,135	$ 141,974
Weighted average years to maturity	2 years	2 years 9 months 18 days	16 years 1 month 6 days	25 years 10 months 24 days	34 years 3 months 18 days