Loans and Allowance for Credit Losses - Troubled Debt Restructurings, Excluding Loans Acquired, Segregated by Class of Loans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	5	4
Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3,729
Troubled debt, balance | $	$ 2,990,845
Real Estate Rental and Leasing | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1,038
Troubled debt, balance | $	$ 1,160,537
Accommodation and Food Services | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	374
Troubled debt, balance | $	$ 859,006
Health Care and Social Assistance | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	206
Troubled debt, balance | $	$ 285,690
Construction | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	164
Troubled debt, balance | $	$ 118,964
Retail Trade | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	143
Troubled debt, balance | $	$ 131,311
Other Services (Except Public Administration) | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	128
Troubled debt, balance | $	$ 56,283
Other | Extended Maturity and Payment Deferral | COVID-19 Pandemic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1,676
Troubled debt, balance | $	$ 379,054
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	54	56
Troubled debt, balance | $	$ 7,513	$ 7,448
Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	32	30
Troubled debt, balance | $	$ 3,138	$ 5,887
Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	22	26
Troubled debt, balance | $	$ 4,375	$ 1,561
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	5	4
Real Estate | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	48	49
Troubled debt, balance | $	$ 5,260	$ 4,585
Real Estate | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	29	26
Troubled debt, balance | $	$ 2,512	$ 3,103
Real Estate | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	19	23
Troubled debt, balance | $	$ 2,748	$ 1,482
Real Estate | Construction and development | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans		1
Troubled debt, balance | $		$ 72
Real Estate | Construction and development | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans		0
Troubled debt, balance | $		$ 0
Real Estate | Construction and development | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans		1
Troubled debt, balance | $		$ 72
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	5	4
Real Estate | Single family residential | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	46	45
Troubled debt, balance | $	$ 5,199	$ 3,957
Real Estate | Single family residential | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	28	25
Troubled debt, balance | $	$ 2,463	$ 2,627
Real Estate | Single family residential | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	18	20
Troubled debt, balance | $	$ 2,736	$ 1,330
Real Estate | Other commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	2	3
Troubled debt, balance | $	$ 61	$ 556
Real Estate | Other commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1	1
Troubled debt, balance | $	$ 49	$ 476
Real Estate | Other commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	1	2
Troubled debt, balance | $	$ 12	$ 80
Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	6	7
Troubled debt, balance | $	$ 2,253	$ 2,863
Commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	4
Troubled debt, balance | $	$ 626	$ 2,784
Commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	3
Troubled debt, balance | $	$ 1,627	$ 79
Commercial | Commercial | Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	6	7
Troubled debt, balance | $	$ 2,253	$ 2,863
Commercial | Commercial | Loans, Excluding Acquired Loans | Accruing TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	4
Troubled debt, balance | $	$ 626	$ 2,784
Commercial | Commercial | Loans, Excluding Acquired Loans | Nonaccrual TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans	3	3
Troubled debt, balance | $	$ 1,627	$ 79