Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 12,990,779	$ 7,271,147
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans		1,905,879
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans		2,112,162
Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans		232,076
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	7,594,212	4,250,117
Commercial Portfolio Segment [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	7,167,397	3,954,721
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	192,013	120,746
Commercial Portfolio Segment [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	233,479	172,555
Commercial Portfolio Segment [Member] | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,323	2,095
Commercial Portfolio Segment [Member] | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,217,300
Commercial Portfolio Segment [Member] | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	3,973,140
Commercial Portfolio Segment [Member] | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	403,772
Commercial Originated Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	4,105,049	3,130,721
Commercial Originated Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,934,033	2,942,826
Commercial Originated Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	81,947	65,943
Commercial Originated Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	87,999	119,857
Commercial Originated Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,070	2,095
Commercial Originated Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,901,526	1,521,515
Commercial Originated Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,803,750	1,418,301
Commercial Originated Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	44,809	34,727
Commercial Originated Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	51,898	66,392
Commercial Originated Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,069	2,095
Commercial Originated Portfolio | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	1,921,799	1,424,059
Commercial Originated Portfolio | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,849,315	1,341,202
Commercial Originated Portfolio | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	36,981	31,036
Commercial Originated Portfolio | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	35,502	51,821
Commercial Originated Portfolio | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1	0
Commercial Originated Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	281,724	185,147
Commercial Originated Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	280,968	183,323
Commercial Originated Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	157	180
Commercial Originated Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	599	1,644
Commercial Originated Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Commercial Acquired Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	3,489,163	1,119,396
Commercial Acquired Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,233,364	1,011,895
Commercial Acquired Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	110,066	54,803
Commercial Acquired Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	145,480	52,698
Commercial Acquired Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	253	0
Commercial Acquired Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,315,774	384,364
Commercial Acquired Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,218,848	340,782
Commercial Acquired Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	46,643	28,321
Commercial Acquired Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	50,283	15,261
Commercial Acquired Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Commercial Acquired Portfolio | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	2,051,341	688,103
Commercial Acquired Portfolio | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,897,011	629,430
Commercial Acquired Portfolio | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	61,441	23,926
Commercial Acquired Portfolio | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	92,636	34,747
Commercial Acquired Portfolio | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	253	0
Commercial Acquired Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	122,048	46,929
Commercial Acquired Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	117,505	41,683
Commercial Acquired Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	1,982	2,556
Commercial Acquired Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	2,561	2,690
Commercial Acquired Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0