Income Taxes (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards		$ 41,700,000
Deferred tax assets, state net operating loss carryforward			$ 19,500,000
Tax Credit Carryforward, Valuation Allowance		0
Income Tax Examination, Penalties and Interest Expense		467,000	(135,000)	$ 114,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		896,000	429,000
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance of unrecognized tax benefits		32,226,000	28,255,000	29,004,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions		153,000
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions			(683,000)	(1,054,000)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions		1,295,000	6,554,000	1,433,000
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities		(1,516,000)	0	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations		783,000	1,900,000	1,128,000
Ending balance of unrecognized tax benefits		31,375,000	32,226,000	28,255,000
Current tax expense
Federal		137,162,000	68,984,000	95,151,000
State		14,532,000	11,095,000	21,523,000
Total current tax expense		151,694,000	80,079,000	116,674,000
Deferred Income Tax Expense (Benefit)
Federal		(28,535,000)	50,522,000	(10,944,000)
State		3,000,000	4,076,000	(2,433,000)
Total deferred tax expense		(25,535,000)	54,598,000	(13,377,000)
Total income tax expense	$ 13,900,000	$ 126,159,000	134,677,000	103,297,000
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory rate		21.00%
Income taxes at federal statutory rates		$ 129,755,000	124,330,000	105,758,000
Nontaxable income on loans, leases and investments, net of nondeductible expenses		(1,581,000)	(1,639,000)	(1,796,000)
Excess tax benefits of compensation		1,146,000	1,070,000	371,000
State and local income taxes, including any change in valuation allowance, net of federal income tax benefit		13,850,000	11,985,000	15,081,000
Effect of federal rate change		0	0	(15,736,000)
Tax credits net of amortization		(5,367,000)	(4,474,000)	(2,891,000)
Repayment of claim of right income		(13,926,000)	0	0
Other, net		2,282,000	3,405,000	2,510,000
Total income tax expense	$ 13,900,000	126,159,000	134,677,000	$ 103,297,000
Deferred Tax Assets, Net [Abstract]
Allowance for loan and lease losses		52,293,000	53,073,000
Operating lease liabilities		15,737,000	17,752,000
Executive separation from service agreements		8,989,000	12,334,000
Federal net operating loss carryforward		9,545,000	11,085,000
Employee compensation		16,083,000	13,313,000
Deferred Tax Assets, FDIC-Assisted Transaction Timing Differences		0	8,678,000
Deferred Tax Assets, Other reserves		5,376,000	5,001,000
Other		6,898,000	10,698,000
Deferred tax asset		114,921,000	131,934,000
Deferred Tax Liabilities, accelerated depreciation		14,984,000	51,249,000
Lease financing activities		15,265,000	8,101,000
Operating lease assets		15,670,000	17,837,000
Net unrealized gain on securities included in accumulated other comprehensive loss		24,857,000	1,821,000
Net deferred loan fees and costs		13,975,000	11,781,000
Intangible assets		13,012,000	9,148,000
Deferred Tax Liability, Security, loan and debt valuations		2,051,000	5,767,000
FDIC-assisted transactions timing differences		2,393,000	0
Pension liability		44,549,000	5,079,000
Other		10,193,000	15,993,000
Deferred Tax Liabilities, Gross		156,949,000	126,776,000
Net deferred tax (liability) asset		$ 42,028,000
Net deferred tax (liability) asset			$ 5,158,000