Loans (Summary of the Aging Status of the Recorded Investment in Loans by Portfolio Segment/Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	$ 85,433	$ 63,095
Total loans	15,269,779	14,155,267
Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	30,139
Commercial real estate:
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	42,414	29,545
Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	12
Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	7,988
Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	1,276
Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	3,604
Originated
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	35,381	32,281
Nonaccrual Loans	85,433	63,095
Current	11,723,942	9,652,053
Total loans	11,844,756	9,747,429
Originated | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	33,954	30,904
Originated | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,427	1,377
Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	16,835	16,269
Nonaccrual Loans	30,139	19,691
Current	3,240,113	2,371,646
Total loans	3,287,087	2,407,606
Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	16,835	16,269
Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Commercial real estate:
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	7,549	5,769
Nonaccrual Loans	42,414	29,545
Current	3,470,194	2,716,111
Total loans	3,520,157	2,751,425
Originated | Commercial real estate: | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	6,610	5,756
Originated | Commercial real estate: | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	939	0
Financing receivable, recorded investment accruing loans past due 90 days or more		13
Originated | Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	247	0
Nonaccrual Loans	12	77
Current	566,467	498,078
Total loans	566,726	498,155
Originated | Real estate construction and land development | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	247	0
Originated | Real estate construction and land development | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,688	2,325
Nonaccrual Loans	7,988	8,635
Current	2,397,629	1,956,897
Total loans	2,407,305	1,967,857
Originated | Residential mortgage | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,688	2,325
Originated | Residential mortgage | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,731	3,663
Nonaccrual Loans	1,276	842
Current	1,445,345	1,506,035
Total loans	1,451,352	1,510,540
Originated | Consumer installment | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,731	3,663
Originated | Consumer installment | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,331	4,255
Nonaccrual Loans	3,604	4,305
Current	604,194	603,286
Total loans	612,129	611,846
Originated | Home equity | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,843	2,891
Originated | Home equity | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	488
Financing receivable, recorded investment accruing loans past due 90 days or more		1,364
Non-owner occupied | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	23,021
Non-owner occupied | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	2,680	1,608
Nonaccrual Loans	23,021	5,270
Current	1,940,629	1,511,909
Total loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,793	1,595
Non-owner occupied | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	887
Financing receivable, recorded investment accruing loans past due 90 days or more		13
Vacant land | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	3,337
Vacant land | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	160	83
Nonaccrual Loans	3,337	5,205
Current	36,798	41,736
Total loans	40,295	47,024
Vacant land | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	160	83
Vacant land | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Owner-occupied | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	16,056
Owner-occupied | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,709	4,078
Nonaccrual Loans	16,056	19,070
Current	1,492,767	1,162,466
Total loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,657	4,078
Owner-occupied | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	$ 52
Financing receivable, recorded investment accruing loans past due 90 days or more		$ 0