Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current tax expense
Federal	$ 41,996	$ 85,875	$ 108,639
State	7,080	9,212	23,101
Total current tax expense	49,076	95,087	131,740
Deferred Income Tax Expense (Benefit)
Federal	38,974	(27,344)	(12,127)
State	8,915	(7,921)	(4,510)
Total deferred tax expense (benefit)	47,889	(35,265)	(16,637)
Total income tax expense	96,965	59,822	115,103
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory rate	35.00%
Income taxes at statutory rates	92,633	67,959	108,546
Increase (reduction) in income taxes resulting from: [Abstract]
Nontaxable income on loans, leases and investments, net of nondeductible expenses	(1,185)	(1,309)	(1,481)
State and local income taxes, including change in valuation allowance, net of federal income tax benefit	10,397	839	12,084
Tax credits	(5,569)	(7,279)	(5,166)
Other, net	689	(388)	1,120
Total income tax expense	96,965	59,822	115,103
Income tax expense reduction, resulting from favorable outcome of state tax audits		6,449
Deferred Tax Assets, Net [Abstract]
Allowance for loan and lease losses	90,790	124,928
Pension liability	2,593	46,178
Executive separation from service agreements	9,940	10,123
State operating loss carryforwards	79	652
Unrealized loss on cash flow hedge	2,786	4,106
Net unrealized loss on securities included in accumulated other comprehensive loss	6,541	0
Other	17,884	19,465
Gross deferred tax asset	130,613	205,452
Accelerated depreciation	6,226	12,465
Lease financing activities	10,216	10,366
Net unrealized gains on securities included in accumulated other comprehensive loss	0	13,292
Net deferred loan fees and costs	4,115	3,714
Intangible assets	11,929	11,897
Gain on FDIC-assisted transactions, deferred for tax purposes	57,895	29,694
Other	6,352	5,373
Deferred tax liability	96,733	86,801
Net deferred tax assets	$ 33,880	$ 118,651