Loans and Allowance for Loan Losses -d (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Loans and Allowance for Loan Losses
Loans, net	$ 7,868,840	$ 6,643,326	$ 6,129,228
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	5,564,307	5,241,041	4,472,668
Less allowance for non-acquired loan losses	(38,449)	(36,960)	(35,115)	$ (34,090)
Loans, net	5,525,858	5,204,081	4,437,553
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	631,896		696,314
Loans, net	627,340	602,546	598,601
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	1,715,642		999,238
Loans, net	1,715,642	836,699	991,505
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	266,484		298,537
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,450,542	1,295,179	972,834
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	646,544	580,464	447,197
Less allowance for non-acquired loan losses	(4,649)	(4,091)	(4,482)	(4,116)
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	803,998	714,715	525,637
Less allowance for non-acquired loan losses	(5,464)	(4,980)	(3,923)	(3,568)
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	57,343		51,379
Commercial non-owner occupied real estate | Acquired credit impaired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	214,562		237,393
Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	217,850		36,530
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	141,897		13,024
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,200,004	1,177,745	1,060,513
Less allowance for non-acquired loan losses	(7,894)	(8,022)	(8,179)	(8,341)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	238,612		37,356
Consumer real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,649,456	1,580,839	1,386,516
Consumer real estate | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	396,806	383,218	325,962
Less allowance for non-acquired loan losses	(3,456)	(3,211)	(3,097)	(2,929)
Consumer real estate | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	2,005,371	1,918,481	1,710,577
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	1,252,650	1,197,621	1,060,554
Less allowance for non-acquired loan losses	(8,108)	(7,820)	(7,345)	(7,212)
Consumer real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	58,688		67,612
Consumer real estate | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	186,411		184,388
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	550,578		494,472
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	725,974	671,398	553,527
Less allowance for non-acquired loan losses	(5,124)	(4,842)	(3,951)	(3,974)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	26,225		28,948
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	136,309		21,109
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	182,416	178,238	175,217
Less allowance for non-acquired loan losses	(1,345)	(1,542)	(1,802)	(1,963)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	92,044		49,123
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	340,292	324,238	247,502
Less allowance for non-acquired loan losses	(2,443)	(2,350)	(1,785)	(1,694)
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	151,941		163,236
Commercial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	3,558,936	3,322,560	2,762,091
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	15,623	13,404	76,559
Less allowance for non-acquired loan losses	34	$ (102)	(551)	$ (293)
Commercial loans 1000000 or more | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	$ 8,594		$ 12,445