Stockholders Equity (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of activity in accumulated other comprehensive income
Net income (loss)	$ 139,699	$ (856)	$ (131,859)
Investment securities available for sale
Net unrealized gains (losses)	71,606	(38,278)	113,455
Reclassification adjustment for net (gains) losses realized in net income	1,112	(24,917)	(8,774)
Income tax (expense) benefit	(28,566)	24,785	(37,534)
Other comprehensive income (loss) on investment securities available for sale	44,152	(38,410)	67,147
Defined benefit pension and postretirement obligations:
Prior service cost, net of amortization	467	467	467
Net gain (loss), net of amortization	(14,810)	2,271	2,736
Income tax (expense) benefit	5,674	(1,106)	(1,236)
Other comprehensive income on pension and postretirement obligations	(8,669)	1,632	1,967
Derivatives used in cash flow hedging relationships
Net unrealized losses	(557)	(4,542)	(1,814)
Reclassification adjustment for net losses and interest expense for interest differential on derivatives realized in net income	4,708	6,013	8,540
Income tax (expense) benefit	(1,658)	(499)	(2,718)
Other comprehensive income (loss) on cash flow hedging relationships	2,493	972	4,008
Total other comprehensive income (loss)	37,976	(35,806)	73,122
Comprehensive income (loss)	$ 177,675	$ (36,662)	$ (58,737)