Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards	$ 14,300
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	357	$ 298	$ 1,127
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance of unrecognized tax benefits	5,975	3,865	2,823
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(327)	(79)	0
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	23,231	2,189	1,042
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0	0	0
Ending balance of unrecognized tax benefits	28,879	5,975	3,865
Current tax expense
Federal	84,946	105,367	84,430
State	7,493	16,111	13,941
Total current tax expense	92,439	121,478	98,371
Deferred Income Tax Expense (Benefit)
Federal	23,144	(2,758)	(30,658)
State	10,002	3,308	(2,681)
Total deferred tax expense (benefit)	33,146	550	(33,339)
Total income tax expense	$ 125,585	122,028	65,032
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory rate	35.00%
Income taxes at statutory rates	$ 122,874	116,345	71,258
Nontaxable income on loans, leases and investments, net of nondeductible expenses	(2,901)	(3,020)	(1,832)
State and local income taxes, including change in valuation allowance, net of federal income tax benefit	11,372	12,622	7,319
Effective Income Tax Rate Reconciliation, Acquisition Stock Settlement, Amount	(98)	0	(10,185)
Tax credits	(4,138)	(3,060)	(2,896)
Other, net	(1,524)	(859)	1,368
Total income tax expense	125,585	122,028	$ 65,032
Deferred Tax Assets, Net [Abstract]
Allowance for loan and lease losses	80,939	78,878
Pension liability	15,679	7,206
Executive separation from service agreements	14,278	9,856
State operating loss carryforwards	0	21
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	5,019	0
Unrealized loss on cash flow hedge	0	537
Net unrealized loss on securities included in accumulated other comprehensive loss	26,832	9,379
Deferred Tax Assets, Property, Plant and Equipment	133	13,195
Deferred Tax Assets, FDIC-Assisted Transaction Timing Differences, Amount	52,579	66,456
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves	10,504	10,772
Other	26,663	29,279
Gross deferred tax asset	232,626	225,579
Lease financing activities	11,651	15,492
Net deferred loan fees and costs	10,867	6,051
Intangible assets	6,335	2,040
Deferred Tax Liability, Mark to Market Section 475, Amount	22,656	31,486
Other	8,501	12,026
Deferred tax liability	60,010	67,095
Net deferred tax assets	$ 172,616	$ 158,484