Loans and Allowance for Loan Losses, Financing Receivables Past Due (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		$ 19,787,876	$ 17,707,549	$ 15,633,116
Nonaccrual loans	[1]	53,939	77,248
Total Loans		19,787,876	17,707,549
Currently performing impaired loans		35,800	52,500
Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		13,249	14,743
Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		7,666	10,586
Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		33,887	58,301
Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		1,615	1,558
Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		19,677,520	17,545,113
Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		35,502	59,859
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		7,709,218	7,164,954	6,669,610
Consumer Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		3,068,625	2,844,447	2,561,214
Nonaccrual loans	[1]	20,995	22,564
Total Loans		3,068,625	2,844,447
Consumer Real Estate | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		3,014	3,689
Consumer Real Estate | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		3,671	5,505
Consumer Real Estate | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		8,162	18,059
Consumer Real Estate | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		168	0
Consumer Real Estate | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		3,032,615	2,794,630
Consumer Real Estate | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		8,330	18,059
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,430,483	2,072,455	1,908,288
Nonaccrual loans	[1]	542	2,020
Total Loans		2,430,483	2,072,455
Construction and Land Development | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		1,286	2,108
Construction and Land Development | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		1,736	1,367
Construction and Land Development | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,087	3,759
Construction and Land Development | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		0	0
Construction and Land Development | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,424,832	2,063,201
Construction and Land Development | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,087	3,759
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		6,290,296	5,271,421	4,141,341
Nonaccrual loans	[1]	14,294	23,022
Total Loans		6,290,296	5,271,421
Commercial and Industrial | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		329	623
Commercial and Industrial | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		1,391	38
Commercial and Industrial | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		10,312	21,451
Commercial and Industrial | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		946	1,082
Commercial and Industrial | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		6,263,024	5,225,205
Commercial and Industrial | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		11,258	22,533
Consumer and Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		289,254	354,272	$ 352,663
Nonaccrual loans	[1]	148	983
Total Loans		289,254	354,272
Consumer and Other | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		0	0
Consumer and Other | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		0	0
Consumer and Other | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,168	3,276
Consumer and Other | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		501	476
Consumer and Other | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		286,437	349,537
Consumer and Other | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,669	3,752
Commercial Real Estate Owner Occupied | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	[1]	10,791	16,025
Total Loans		2,669,766	2,653,433
Commercial Real Estate Owner Occupied | Commercial Real Estate | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		3,366	2,664
Commercial Real Estate Owner Occupied | Commercial Real Estate | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		863	874
Commercial Real Estate Owner Occupied | Commercial Real Estate | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		4,361	10,170
Commercial Real Estate Owner Occupied | Commercial Real Estate | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		0	0
Commercial Real Estate Owner Occupied | Commercial Real Estate | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		2,650,385	2,623,700
Commercial Real Estate Owner Occupied | Commercial Real Estate | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		4,361	10,170
Commercial Real Estate All Other | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	[1]	7,169	12,634
Total Loans		5,039,452	4,511,521
Commercial Real Estate All Other | Commercial Real Estate | Purchase credit impaired, accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		5,254	5,659
Commercial Real Estate All Other | Commercial Real Estate | Purchase credit impaired, nonaccruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans		5	2,802
Commercial Real Estate All Other | Commercial Real Estate | Financing Receivables 30 To 89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		6,797	1,586
Commercial Real Estate All Other | Commercial Real Estate | Financing Receivables, Equal to Greater than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		0	0
Commercial Real Estate All Other | Commercial Real Estate | Current and accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		5,020,227	4,488,840
Commercial Real Estate All Other | Commercial Real Estate | Past Due and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans		$ 6,797	$ 1,586

[1] Approximately $35.8 million and $52.5 million of nonaccrual loans as of December 31, 2019 and December 31, 2018, respectively, were performing pursuant to their contractual terms at those dates.