Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 15,269,779	$ 14,155,267
Originated Loan Portfolio [Member] | Originated Loan Portfolio [Member]
Financing Receivable, Recorded Investment [Line Items]
Minimum Value of Loan Requires Group Loan Authority Approval	1,300
Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	9,511,867	8,460,527
Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	8,998,284	8,038,463
Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	283,400	204,706
Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	225,924	216,353
Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	4,259	1,005
Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Minimum Value of Loan Requires Group Loan Authority Approval	3,000
Loans	4,002,568	3,385,642
Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	4,912,087	4,500,670
Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	597,212	574,215
Originated
Financing Receivable, Recorded Investment [Line Items]
Loans	11,844,756	9,747,429
Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,287,087	2,407,606
Originated | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	3,520,157	2,751,425
Originated | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	566,726	498,155
Originated | Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	7,373,970	5,657,186
Originated | Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	7,045,203	5,488,571
Originated | Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	164,802	66,100
Originated | Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	159,733	102,515
Originated | Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	4,232	0
Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,287,087	2,407,606
Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,118,894	2,316,464
Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	87,222	41,059
Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	77,036	50,083
Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	3,935	0
Originated | Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	3,520,157	2,751,425
Originated | Commercial Loan Portfolio | Commercial real estate: | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,369,269	2,677,579
Originated | Commercial Loan Portfolio | Commercial real estate: | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	71,472	24,204
Originated | Commercial Loan Portfolio | Commercial real estate: | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	79,119	49,642
Originated | Commercial Loan Portfolio | Commercial real estate: | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	297	0
Originated | Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	566,726	498,155
Originated | Commercial Loan Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	557,040	494,528
Originated | Commercial Loan Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	6,108	837
Originated | Commercial Loan Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	3,578	2,790
Originated | Commercial Loan Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Acquired
Financing Receivable, Recorded Investment [Line Items]
Loans	3,425,023	4,407,838
Acquired | Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	2,137,897	2,803,341
Acquired | Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,953,081	2,549,892
Acquired | Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	118,598	138,606
Acquired | Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	66,191	113,838
Acquired | Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	27	1,005
Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	715,481	978,036
Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	655,883	873,861
Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	36,809	68,418
Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	22,773	35,539
Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	16	218
Acquired | Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	1,391,930	1,749,245
Acquired | Commercial Loan Portfolio | Commercial real estate: | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,267,950	1,603,685
Acquired | Commercial Loan Portfolio | Commercial real estate: | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	81,692	67,970
Acquired | Commercial Loan Portfolio | Commercial real estate: | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	42,277	76,803
Acquired | Commercial Loan Portfolio | Commercial real estate: | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	11	787
Acquired | Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	30,486	76,060
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	29,248	72,346
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	97	2,218
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	1,141	1,496
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Owner-occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	2,059,557	1,813,562
Owner-occupied | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,430,948	1,133,609
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	32,056	19,438
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	50,286	32,567
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	242	0
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	546,025	627,948
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	500,072	580,127
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	28,909	23,998
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	17,033	23,036
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	11	787
Non-owner occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	2,785,020	2,606,761
Non-owner occupied | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,901,822	1,504,195
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	39,416	4,728
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	25,092	9,864
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	818,690	1,087,974
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	740,900	995,709
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	52,546	43,645
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	25,244	48,620
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Vacant land | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	67,510	80,347
Vacant land | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	40,295	47,024
Vacant land | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	40,295	47,024
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	36,499	39,775
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	0	38
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	3,741	7,211
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	55	0
Vacant land | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	27,215	33,323
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	26,978	27,849
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	237	327
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	0	5,147
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0