Loans and Allowance for Credit Losses - Financing Receivables Past Due (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Loans	$ 24,499,022	$ 23,414,262
Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	3,124,275	3,048,822
Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	5,426,583	5,221,704
Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	3,813,252	3,680,684
Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	3,277,029	2,903,017
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	8,370,384	8,074,546
Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	487,499	485,489
30-59 days past due
Financing Receivable, Past Due [Line Items]
Loans	22,505	17,573
30-59 days past due | Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	2,443	727
30-59 days past due | Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	309	1,434
30-59 days past due | Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	5,950	8,710
30-59 days past due | Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	598	61
30-59 days past due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	11,059	4,926
30-59 days past due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	2,146	1,715
60-89 days past due
Financing Receivable, Past Due [Line Items]
Loans	6,965	3,367
60-89 days past due | Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	0	0
60-89 days past due | Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	1,387	0
60-89 days past due | Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	3,174	122
60-89 days past due | Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	0	0
60-89 days past due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	1,624	2,677
60-89 days past due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	780	568
90 days or more past due
Financing Receivable, Past Due [Line Items]
Loans	10,353	15,331
90 days or more past due | Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	1,915	2,426
90 days or more past due | Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	701	645
90 days or more past due | Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	2,643	4,450
90 days or more past due | Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	127	127
90 days or more past due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	4,562	7,311
90 days or more past due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	405	372
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	39,823	36,271
Financial Asset, Past Due | Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	4,358	3,153
Financial Asset, Past Due | Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	2,397	2,079
Financial Asset, Past Due | Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	11,767	13,282
Financial Asset, Past Due | Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	725	188
Financial Asset, Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	17,245	14,914
Financial Asset, Past Due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	3,331	2,655
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Loans	24,459,199	23,377,991
Financial Asset, Not Past Due | Commercial real estate - Owner occupied
Financing Receivable, Past Due [Line Items]
Loans	3,119,917	3,045,669
Financial Asset, Not Past Due | Commercial real estate - Non-owner occupied
Financing Receivable, Past Due [Line Items]
Loans	5,424,186	5,219,625
Financial Asset, Not Past Due | Consumer real estate – mortgage
Financing Receivable, Past Due [Line Items]
Loans	3,801,485	3,667,402
Financial Asset, Not Past Due | Construction and land development
Financing Receivable, Past Due [Line Items]
Loans	3,276,304	2,902,829
Financial Asset, Not Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	8,353,139	8,059,632
Financial Asset, Not Past Due | Consumer and other
Financing Receivable, Past Due [Line Items]
Loans	$ 484,168	$ 482,834