Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Loans and Allowance for Loan Losses
Loans, net	$ 11,089,600	$ 10,962,037	$ 10,589,521
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	8,310,613	7,933,286	6,762,512
Less allowance for non-acquired loan losses	(52,008)	(51,194)	(45,203)	$ (43,448)
Loans, net	8,258,605	7,882,092	6,717,309
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	456,772	489,723	601,358
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	2,378,737	2,594,826	3,274,938
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	199,701	207,482	248,766
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,425,967	2,256,996	1,922,065
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	810,551	841,445	871,141
Less allowance for non-acquired loan losses	(5,371)	(5,682)	(5,847)	(5,921)
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	1,615,416	1,415,551	1,050,924
Less allowance for non-acquired loan losses	(9,740)	(8,754)	(6,798)	(6,525)
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	32,257	32,942	46,219
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	173,707	196,764	233,277
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	113,572	165,070	349,532
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	629,394	679,253	783,466
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,601,360	1,517,551	1,296,738
Less allowance for non-acquired loan losses	(9,629)	(9,369)	(8,346)	(8,128)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	400,658	421,841	498,541
Consumer loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,513,640	2,431,413	2,061,083
Consumer loans | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	508,326	495,148	448,582
Less allowance for non-acquired loan losses	(3,273)	(3,434)	(3,237)	(3,250)
Consumer loans | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	2,005,314	1,936,265	1,612,501
Less allowance for non-acquired loan losses	(12,058)	(11,913)	(10,193)	(9,668)
Consumer loans | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	225,278	242,425	295,721
Consumer loans | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	610,376	628,813	683,614
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,072,070	1,054,952	872,363
Less allowance for non-acquired loan losses	(7,249)	(7,454)	(6,333)	(5,488)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	10,925	10,043	24,295
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	173,840	212,537	344,171
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	214,235	214,353	198,684
Less allowance for non-acquired loan losses	(1,387)	(1,446)	(1,393)	(1,375)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	120,696	133,110	186,091
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	465,117	448,664	390,784
Less allowance for non-acquired loan losses	(3,195)	(3,101)	(2,899)	(2,788)
Consumer | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	465,117	448,664	390,784
Consumer | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	40,182	42,492	48,801
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	104,923	111,777	133,802
Commercial loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	5,313,632	5,043,852	4,289,850
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	18,224	9,357	20,795
Less allowance for non-acquired loan losses	$ (106)	$ (41)	$ (157)	$ (305)