Loans and Allowance for Loan Losses - (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Loans and Allowance for Loan Losses
Loans, net	$ 10,589,521	$ 10,575,417	$ 7,868,840
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	6,762,512	6,492,155	5,564,307
Less allowance for non-acquired loan losses	(45,203)	(43,448)	(38,449)	$ (36,960)
Loans, net	6,717,309	6,448,707	5,525,858
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	601,358	623,430	631,896
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	3,274,938	3,507,907	1,715,642
Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans			238,612
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	248,766	260,787	266,484
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,922,065	1,839,768	1,450,542
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	871,141	830,875	646,544
Less allowance for non-acquired loan losses	(5,847)	(5,921)	(4,649)	(4,091)
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	1,050,924	1,008,893	803,998
Less allowance for non-acquired loan losses	(6,798)	(6,525)	(5,464)	(4,980)
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	46,219	49,649	57,343
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	233,277	234,595	223,156
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	349,532	403,357
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	783,466	817,166	217,850
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,296,738	1,262,776	1,200,004
Less allowance for non-acquired loan losses	(8,346)	(8,128)	(7,894)	(8,022)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	498,541	521,818
Consumer real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,061,083	1,967,902	1,649,456
Consumer real estate | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	448,582	437,642	396,806
Less allowance for non-acquired loan losses	(3,237)	(3,250)	(3,456)	(3,211)
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	1,612,501	1,530,260	1,252,650
Less allowance for non-acquired loan losses	(10,193)	(9,668)	(8,108)	(7,820)
Consumer real estate | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	295,721	320,591	186,411
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	683,614	710,611	550,578
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	872,363	815,187	725,974
Less allowance for non-acquired loan losses	(6,333)	(5,488)	(5,124)	(4,842)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	24,295	26,946	26,225
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	344,171	398,696	136,309
Commercial and industrial | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans			141,897
Commercial and industrial | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans			136,309
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	198,684	193,847	182,416
Less allowance for non-acquired loan losses	(1,393)	(1,375)	(1,345)	(1,542)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	186,091	196,669	92,044
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	390,784	378,985	340,292
Less allowance for non-acquired loan losses	(2,899)	(2,788)	(2,443)	(2,350)
Consumer | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	390,784	378,985	340,292
Consumer | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	48,801	51,453	58,688
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	133,802	137,710	151,941
Commercial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	4,289,850	4,111,578	3,558,936
Commercial | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	349,532		141,897
Commercial | Acquired non-credit impaired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	498,541		238,612
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	20,795	33,690	15,623
Less allowance for non-acquired loan losses	$ (157)	(305)	$ 34	$ (102)
Other loans | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans		$ 1,289