Loans and Allowance for Loan Losses (Allowance for Loan Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			$ 181,179	$ 128,762
Allowance for loan losses: Net provision for loan losses	$ 18,972	$ 10,080	96,204	22,842
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			(3,027)	(1,984)
Allowance for loan losses: Ending balance	236,061	139,576	236,061	139,576
Allowance for loan losses: Individually evaluated for impairment	21,130	8,618	21,130	8,618
Allowance for loan losses: Amounts related to purchased credit impaired loans	19,708	25,505	19,708	25,505
Allowance for loan losses: Collectively evaluated for impairment	195,223	105,453	195,223	105,453
Loans: Individually evaluated for impairment	256,563	112,443	256,563	112,443
Loans: Purchased credit impaired loans	201,792	249,905	201,792	249,905	$ 225,838	$ 313,685
Loans: Collectively evaluated for impairment	15,612,466	14,400,702	15,612,466	14,400,702
Loans: Total loans	16,070,821	14,763,050	16,070,821	14,763,050	15,703,314
Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans: Total loans	11,972,654		11,972,654		11,560,325
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			6,041	7,546
Allowance for loan losses: Ending balance	10,950	5,133	10,950	5,133
Allowance for loan losses: Individually evaluated for impairment	57	187	57	187
Allowance for loan losses: Amounts related to purchased credit impaired loans	279	885	279	885
Allowance for loan losses: Collectively evaluated for impairment	10,614	4,061	10,614	4,061
Loans: Individually evaluated for impairment	7,655	12,520	7,655	12,520
Loans: Purchased credit impaired loans	8,087	15,280	8,087	15,280
Loans: Collectively evaluated for impairment	1,974,567	1,456,432	1,974,567	1,456,432
Loans: Total loans	1,990,309	1,484,232	1,990,309	1,484,232	1,553,082
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			5,642	6,421
Allowance for loan losses: Ending balance	5,848	7,374	5,848	7,374
Allowance for loan losses: Individually evaluated for impairment	6	21	6	21
Allowance for loan losses: Amounts related to purchased credit impaired loans	484	1,727	484	1,727
Allowance for loan losses: Collectively evaluated for impairment	5,358	5,626	5,358	5,626
Loans: Individually evaluated for impairment	2,062	2,053	2,062	2,053
Loans: Purchased credit impaired loans	8,436	16,336	8,436	16,336
Loans: Collectively evaluated for impairment	936,094	1,067,196	936,094	1,067,196
Loans: Total loans	946,592	1,085,585	946,592	1,085,585	1,151,950
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			25,353	28,660
Allowance for loan losses: Ending balance	24,192	25,790	24,192	25,790
Allowance for loan losses: Individually evaluated for impairment	94	96	94	96
Allowance for loan losses: Amounts related to purchased credit impaired loans	15,949	18,329	15,949	18,329
Allowance for loan losses: Collectively evaluated for impairment	8,149	7,365	8,149	7,365
Loans: Individually evaluated for impairment	3,864	903	3,864	903
Loans: Purchased credit impaired loans	145,273	170,033	145,273	170,033
Loans: Collectively evaluated for impairment	1,888,025	1,842,853	1,888,025	1,842,853
Loans: Total loans	2,037,162	2,013,789	2,037,162	2,013,789	2,049,524
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			24,857	21,430
Allowance for loan losses: Ending balance	25,027	23,252	25,027	23,252
Allowance for loan losses: Individually evaluated for impairment	85	3	85	3
Allowance for loan losses: Amounts related to purchased credit impaired loans	1,334	2,711	1,334	2,711
Allowance for loan losses: Collectively evaluated for impairment	23,608	20,538	23,608	20,538
Loans: Individually evaluated for impairment	1,485	157	1,485	157
Loans: Purchased credit impaired loans	12,045	13,424	12,045	13,424
Loans: Collectively evaluated for impairment	2,047,475	1,976,715	2,047,475	1,976,715
Loans: Total loans	2,061,005	1,990,296	2,061,005	1,990,296	2,093,465
Purchased Credit Impaired [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(146)	(5,451)
Allowance for loan losses: Recoveries			484	3,742
Allowance for loan losses: Net provision for loan losses			(723)	(1,386)
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			(3,027)	(1,984)
Purchased Credit Impaired [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)	(2,353)
Allowance for loan losses: Recoveries			2	20
Allowance for loan losses: Net provision for loan losses			(436)	994
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable				919
Purchased Credit Impaired [Member] | Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(18)	(406)
Allowance for loan losses: Recoveries			98	896
Allowance for loan losses: Net provision for loan losses			(253)	235
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable				(6)
Purchased Credit Impaired [Member] | Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(91)	(748)
Allowance for loan losses: Recoveries			33	5
Allowance for loan losses: Net provision for loan losses			1,685	1,181
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			(3,341)	(2,718)
Purchased Credit Impaired [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(8)	(140)
Allowance for loan losses: Recoveries			112	185
Allowance for loan losses: Net provision for loan losses			(1,633)	(1,232)
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			316	(97)
Non-Purchased Credit Impaired [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(48,493)	(17,561)
Allowance for loan losses: Recoveries			9,860	9,226
Allowance for loan losses: Net provision for loan losses			96,927	24,228
Non-Purchased Credit Impaired [Member] | Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(191)	(464)
Allowance for loan losses: Recoveries			673	386
Allowance for loan losses: Net provision for loan losses			4,862	(1,915)
Non-Purchased Credit Impaired [Member] | Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(827)	(1,483)
Allowance for loan losses: Recoveries			1,422	2,006
Allowance for loan losses: Net provision for loan losses			(216)	(289)
Non-Purchased Credit Impaired [Member] | Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(908)	(1,451)
Allowance for loan losses: Recoveries			497	578
Allowance for loan losses: Net provision for loan losses			964	283
Non-Purchased Credit Impaired [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(17,403)	(10,431)
Allowance for loan losses: Recoveries			4,272	3,418
Allowance for loan losses: Net provision for loan losses			14,514	10,119
Total Commercial & Industrial [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			119,286	64,705
Allowance for loan losses: Ending balance	170,044	78,027	170,044	78,027
Allowance for loan losses: Individually evaluated for impairment	20,888	8,311	20,888	8,311
Allowance for loan losses: Amounts related to purchased credit impaired loans	1,662	1,853	1,662	1,853
Allowance for loan losses: Collectively evaluated for impairment	147,494	67,863	147,494	67,863
Loans: Individually evaluated for impairment	241,497	96,810	241,497	96,810
Loans: Purchased credit impaired loans	27,951	34,832	27,951	34,832
Loans: Collectively evaluated for impairment	8,766,305	8,057,506	8,766,305	8,057,506
Loans: Total loans	9,035,753	8,189,148	9,035,753	8,189,148	8,855,293
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			109,428	51,169
Allowance for loan losses: Ending balance	159,261	63,922	159,261	63,922
Allowance for loan losses: Individually evaluated for impairment	20,665	5,588	20,665	5,588
Allowance for loan losses: Amounts related to purchased credit impaired loans	574	549	574	549
Allowance for loan losses: Collectively evaluated for impairment	138,022	57,785	138,022	57,785
Loans: Individually evaluated for impairment	235,039	75,345	235,039	75,345
Loans: Purchased credit impaired loans	11,534	13,158	11,534	13,158
Loans: Collectively evaluated for impairment	6,887,355	6,257,491	6,887,355	6,257,491
Loans: Total loans	7,133,928	6,345,994	7,133,928	6,345,994	6,995,824
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			9,858	13,536
Allowance for loan losses: Ending balance	10,783	14,105	10,783	14,105
Allowance for loan losses: Individually evaluated for impairment	223	2,723	223	2,723
Allowance for loan losses: Amounts related to purchased credit impaired loans	1,088	1,304	1,088	1,304
Allowance for loan losses: Collectively evaluated for impairment	9,472	10,078	9,472	10,078
Loans: Individually evaluated for impairment	6,458	21,465	6,458	21,465
Loans: Purchased credit impaired loans	16,417	21,674	16,417	21,674
Loans: Collectively evaluated for impairment	1,878,950	1,800,015	1,878,950	1,800,015
Loans: Total loans	$ 1,901,825	$ 1,843,154	1,901,825	1,843,154	$ 1,859,469
Total Commercial & Industrial [Member] | Purchased Credit Impaired [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(28)	(1,804)
Allowance for loan losses: Recoveries			239	2,636
Allowance for loan losses: Net provision for loan losses			(86)	(2,564)
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			(2)	(82)
Total Commercial & Industrial [Member] | Purchased Credit Impaired [Member] | Total Commercial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs				(1,425)
Allowance for loan losses: Recoveries			76	1,699
Allowance for loan losses: Net provision for loan losses			54	(950)
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable			(2)	314
Total Commercial & Industrial [Member] | Purchased Credit Impaired [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)	(379)
Allowance for loan losses: Recoveries			163	937
Allowance for loan losses: Net provision for loan losses			(140)	(1,614)
Allowance for loan losses: Increase (decrease) in FDIC loss share receivable				(396)
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired [Member] | Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(29,164)	(3,732)
Allowance for loan losses: Recoveries			2,996	2,838
Allowance for loan losses: Net provision for loan losses			76,803	16,030
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired [Member] | Total Commercial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(27,504)	(3,068)
Allowance for loan losses: Recoveries			2,709	2,589
Allowance for loan losses: Net provision for loan losses			74,500	13,594
Total Commercial & Industrial [Member] | Non-Purchased Credit Impaired [Member] | Total Commercial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(1,660)	(664)
Allowance for loan losses: Recoveries			287	249
Allowance for loan losses: Net provision for loan losses			$ 2,303	$ 2,436