Summary of Significant Accounting Policies - Additional information (Details) $ in Thousands		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($) lease	Jan. 01, 2018 USD ($)
Schedule of Significant Accounting Policies [Line Items]
Reserve and clearing requirement balance		$ 0	$ 0
Reclassification of unrealized losses on equity investments to retained earnings - ASU 2016-01						$ (188)
Aggregate carrying value of properties foreclosed on		19,400
Net valuation adjustments subsequent to foreclosures		167
Proceeds from sales of OREO		3,197	6,667	$ 14,802
Impairment of investments in affordable housing partnership		0	0	4,846
Payments of cash dividends on Common Stock		70,900	71,600
Loss Contingency Accrual		440	$ 755
Reclassification of stranded tax effects to retained earnings - ASU 2018-02				0
Right-of-use asset		58,593
Operating lease liabilities		60,506
Accounting Standards Update 2016-02
Schedule of Significant Accounting Policies [Line Items]
Number of operating leases | lease					96
Right-of-use asset					$ 64,200
Operating lease liabilities					$ 64,300
Retained Earnings
Schedule of Significant Accounting Policies [Line Items]
Reclassification of unrealized losses on equity investments to retained earnings - ASU 2016-01		$ (469)				$ (469)
Reclassification of stranded tax effects to retained earnings - ASU 2018-02				$ 3,597
Minimum | Accounting Standards Update 2016-13 | Subsequent Event
Schedule of Significant Accounting Policies [Line Items]
Increase in allowance for loan losses	30.00%
Decline in basis points for Tier 1 Common Equity Risk-Based Ratio	0.22%
Minimum | Buildings
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		15 years
Minimum | Furniture , fixture and equipment
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		3 years
Minimum | Computer equipment
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		1 year
Minimum | Computer Software
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		1 year
Maximum | Accounting Standards Update 2016-13 | Subsequent Event
Schedule of Significant Accounting Policies [Line Items]
Increase in allowance for loan losses	40.00%
Decline in basis points for Tier 1 Common Equity Risk-Based Ratio	0.29%
Maximum | Buildings
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		39 years
Maximum | Furniture , fixture and equipment
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		10 years
Maximum | Computer equipment
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		5 years
Maximum | Computer Software
Schedule of Significant Accounting Policies [Line Items]
Estimated useful lives		5 years
Core deposits | Minimum
Schedule of Significant Accounting Policies [Line Items]
Amortization Period		7 years
Core deposits | Maximum
Schedule of Significant Accounting Policies [Line Items]
Amortization Period		10 years