Loans and Allowance for Loan Losses (Allowance for Loan Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			$ 229,418	$ 181,179
Allowance for loan losses: Net provision for loan losses	$ 14,951	$ 17,196	30,942	77,232
Allowance for loan losses: Decrease in FDIC loss share receivable			(2,526)	(3,437)
Allowance for loan losses: Ending balance	221,865	226,086	221,865	226,086
Allowance for loan losses: Individually evaluated for impairment	24,896	13,349	24,896	13,349
Allowance for loan losses: Amounts related to purchased credit impaired loans	15,132	19,590	15,132	19,590
Allowance for loan losses: Collectively evaluated for impairment	181,837	193,147	181,837	193,147
Loans: Individually evaluated for impairment	278,015	248,967	278,015	248,967
Loans: Purchased credit impaired loans	163,155	209,924	163,155	209,924	$ 190,915	$ 225,838
Loans: Collectively evaluated for impairment	18,032,671	15,576,905	18,032,671	15,576,905
Loans receivable	18,473,841	16,035,796	18,473,841	16,035,796	16,752,151
Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans receivable	13,886,631		13,886,631		12,545,507
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			13,509	6,041
Allowance for loan losses: Ending balance	13,540	12,799	13,540	12,799
Allowance for loan losses: Individually evaluated for impairment	1,402	72	1,402	72
Allowance for loan losses: Amounts related to purchased credit impaired loans	192	741	192	741
Allowance for loan losses: Collectively evaluated for impairment	11,946	11,986	11,946	11,986
Loans: Individually evaluated for impairment	14,913	7,803	14,913	7,803
Loans: Purchased credit impaired loans	6,247	10,752	6,247	10,752
Loans: Collectively evaluated for impairment	2,380,513	2,005,916	2,380,513	2,005,916
Loans receivable	2,401,673	2,024,471	2,401,673	2,024,471	2,013,890
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			6,271	5,642
Allowance for loan losses: Ending balance	7,049	5,006	7,049	5,006
Allowance for loan losses: Individually evaluated for impairment	1	1	1	1
Allowance for loan losses: Amounts related to purchased credit impaired loans	239	575	239	575
Allowance for loan losses: Collectively evaluated for impairment	6,809	4,430	6,809	4,430
Loans: Individually evaluated for impairment	847	1,247	847	1,247
Loans: Purchased credit impaired loans	4,160	8,761	4,160	8,761
Loans: Collectively evaluated for impairment	1,308,515	870,580	1,308,515	870,580
Loans receivable	1,313,522	880,588	1,313,522	880,588	1,010,879
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			25,361	25,353
Allowance for loan losses: Ending balance	23,380	23,474	23,380	23,474
Allowance for loan losses: Individually evaluated for impairment	172	167	172	167
Allowance for loan losses: Amounts related to purchased credit impaired loans	12,622	15,430	12,622	15,430
Allowance for loan losses: Collectively evaluated for impairment	10,586	7,877	10,586	7,877
Loans: Individually evaluated for impairment	3,466	1,068	3,466	1,068
Loans: Purchased credit impaired loans	129,198	151,674	129,198	151,674
Loans: Collectively evaluated for impairment	2,361,259	1,864,908	2,361,259	1,864,908
Loans receivable	2,493,923	2,017,650	2,493,923	2,017,650	2,146,713
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			26,142	24,857
Allowance for loan losses: Ending balance	28,435	23,359	28,435	23,359
Allowance for loan losses: Individually evaluated for impairment	283	41	283	41
Allowance for loan losses: Amounts related to purchased credit impaired loans	942	1,257	942	1,257
Allowance for loan losses: Collectively evaluated for impairment	27,210	22,061	27,210	22,061
Loans: Individually evaluated for impairment	1,053	166	1,053	166
Loans: Purchased credit impaired loans	8,280	12,826	8,280	12,826
Loans: Collectively evaluated for impairment	2,083,954	2,051,376	2,083,954	2,051,376
Loans receivable	2,093,287	2,064,368	2,093,287	2,064,368	2,059,931
Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(297)	(78)
Allowance for loan losses: Recoveries			224	292
Allowance for loan losses: Net provision for loan losses			(622)	(307)
Allowance for loan losses: Decrease in FDIC loss share receivable			(2,526)	(3,437)
Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs				(1)
Allowance for loan losses: Recoveries				2
Allowance for loan losses: Net provision for loan losses			(61)	26
Allowance for loan losses: Decrease in FDIC loss share receivable
Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(58)	(18)
Allowance for loan losses: Recoveries			39	53
Allowance for loan losses: Net provision for loan losses			(148)	(117)
Allowance for loan losses: Decrease in FDIC loss share receivable
Purchased Credit Impaired Loans [Member] | Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(86)	(23)
Allowance for loan losses: Recoveries			19	3
Allowance for loan losses: Net provision for loan losses			(10)	1,165
Allowance for loan losses: Decrease in FDIC loss share receivable			(2,344)	(3,378)
Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(153)	(8)
Allowance for loan losses: Recoveries			71	106
Allowance for loan losses: Net provision for loan losses			(112)	(1,290)
Allowance for loan losses: Decrease in FDIC loss share receivable			(135)	(98)
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(42,806)	(36,054)
Allowance for loan losses: Recoveries			6,910	6,952
Allowance for loan losses: Net provision for loan losses			31,564	77,539
Non-Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(160)	(191)
Allowance for loan losses: Recoveries			398	268
Allowance for loan losses: Net provision for loan losses			(146)	6,654
Non-Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(114)	(592)
Allowance for loan losses: Recoveries			716	1,125
Allowance for loan losses: Net provision for loan losses			343	(1,087)
Non-Purchased Credit Impaired Loans [Member] | Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(690)	(592)
Allowance for loan losses: Recoveries			262	480
Allowance for loan losses: Net provision for loan losses			868	466
Non-Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(15,107)	(11,268)
Allowance for loan losses: Recoveries			3,475	3,039
Allowance for loan losses: Net provision for loan losses			14,254	8,021
Total Commercial & Industrial [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			158,135	119,286
Allowance for loan losses: Ending balance	149,461	161,448	149,461	161,448
Allowance for loan losses: Individually evaluated for impairment	23,038	13,068	23,038	13,068
Allowance for loan losses: Amounts related to purchased credit impaired loans	1,137	1,587	1,137	1,587
Allowance for loan losses: Collectively evaluated for impairment	125,286	146,793	125,286	146,793
Loans: Individually evaluated for impairment	257,736	238,683	257,736	238,683
Loans: Purchased credit impaired loans	15,270	25,911	15,270	25,911
Loans: Collectively evaluated for impairment	9,898,430	8,784,125	9,898,430	8,784,125
Loans receivable	10,171,436	9,048,719	10,171,436	9,048,719	9,520,738
Total Commercial & Industrial [Member] | Total Commercial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			147,052	109,428
Allowance for loan losses: Ending balance	137,363	150,772	137,363	150,772
Allowance for loan losses: Individually evaluated for impairment	22,758	12,885	22,758	12,885
Allowance for loan losses: Amounts related to purchased credit impaired loans	395	572	395	572
Allowance for loan losses: Collectively evaluated for impairment	114,210	137,315	114,210	137,315
Loans: Individually evaluated for impairment	250,256	232,785	250,256	232,785
Loans: Purchased credit impaired loans	5,422	10,483	5,422	10,483
Loans: Collectively evaluated for impairment	7,837,426	6,889,251	7,837,426	6,889,251
Loans receivable	8,093,104	7,132,519	8,093,104	7,132,519	7,613,917
Total Commercial & Industrial [Member] | Total Commercial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			11,083	9,858
Allowance for loan losses: Ending balance	12,098	10,676	12,098	10,676
Allowance for loan losses: Individually evaluated for impairment	280	183	280	183
Allowance for loan losses: Amounts related to purchased credit impaired loans	742	1,015	742	1,015
Allowance for loan losses: Collectively evaluated for impairment	11,076	9,478	11,076	9,478
Loans: Individually evaluated for impairment	7,480	5,898	7,480	5,898
Loans: Purchased credit impaired loans	9,848	15,428	9,848	15,428
Loans: Collectively evaluated for impairment	2,061,004	1,894,874	2,061,004	1,894,874
Loans receivable	$ 2,078,332	$ 1,916,200	2,078,332	1,916,200	$ 1,906,821
Total Commercial & Industrial [Member] | Purchased Credit Impaired Loans [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs				(28)
Allowance for loan losses: Recoveries			95	128
Allowance for loan losses: Net provision for loan losses			(291)	(91)
Allowance for loan losses: Decrease in FDIC loss share receivable			(47)	39
Total Commercial & Industrial [Member] | Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs
Allowance for loan losses: Recoveries			2	8
Allowance for loan losses: Net provision for loan losses			(46)	79
Allowance for loan losses: Decrease in FDIC loss share receivable			(47)	39
Total Commercial & Industrial [Member] | Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs				(28)
Allowance for loan losses: Recoveries			93	120
Allowance for loan losses: Net provision for loan losses			(245)	(170)
Allowance for loan losses: Decrease in FDIC loss share receivable
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired Loans [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(26,735)	(23,411)
Allowance for loan losses: Recoveries			2,059	2,040
Allowance for loan losses: Net provision for loan losses			16,245	63,485
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(26,218)	(22,212)
Allowance for loan losses: Recoveries			1,816	1,802
Allowance for loan losses: Net provision for loan losses			14,804	61,628
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired Loans [Member] | Total Commercial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(517)	(1,199)
Allowance for loan losses: Recoveries			243	238
Allowance for loan losses: Net provision for loan losses			$ 1,441	$ 1,857