Income Taxes (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Gross deferred tax assets:
Allowance for loan losses	$ 146,027	$ 160,786
Allowance for other losses	13,714	12,154
Accrued liabilities	11,506	6,548
Deferred compensation	24,638	23,188
Securities valuation adjustment	17,978	18,964
Benefit of tax loss and credit carryforwards	51,835	78,968
Nonaccrual interest	4,042	7,460
Other	7,017	4,185
Total gross deferred tax assets	276,757	312,253
Valuation allowance for deferred tax assets	0	5,984
	276,757	306,269
Gross deferred tax liabilities
FHLB stock dividends	10,424	10,276
Prepaid expenses	49,828	43,467
Intangible amortization	28,274	27,382
Mortgage banking activity	4,796	14,213
Deferred loan fee income	22,914	21,850
State income taxes	20,418	22,656
Leases	3,955	5,246
Depreciation	23,368	13,593
Other	1,805	1,869
Total gross deferred tax liabilities	165,782	160,552
Net deferred tax assets	110,975	145,717
Tax effect of unrealized gain related to available for sale securities	(62,447)	(32,092)
Tax effect of unrealized loss related to pension and postretirement benefits	21,219	15,482
	41,228	16,610
Net deferred tax assets including tax effected items	$ 69,747	$ 129,107