Consolidated Statement of Other Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Summary of activity in accumulated other comprehensive income
Net income (loss)	$ 42,633	$ 22,853
Investment securities available for sale
Net unrealized gains (losses)	(1,914)	27,585
Reclassification adjustment for net (gains) losses realized in net income	(40)	22
Income tax (expense) benefit	762	(10,708)
Other comprehensive income (loss) on investment securities available for sale	(1,192)	16,899
Defined benefit pension and postretirement obligations:
Prior service cost, net of amortization	60	117
Net loss, net of amortization	640	451
Income tax expense	(273)	(221)
Other comprehensive income on pension and postretirement obligations	427	347
Derivatives used in cash flow hedging relationships
Net unrealized losses	10	450
Reclassification adjustment for net losses and interest expense for interest differential on derivatives realized in net income	731	982
Income tax (expense) benefit	(300)	(573)
Other comprehensive income (loss) on cash flow hedging relationships	441	859
Other comprehensive income	(324)	18,105
Comprehensive income (loss)	$ 42,309	$ 40,958