Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Loans and Allowance for Loan Losses
Loans, net	$ 11,167,979		$ 10,962,037	$ 10,778,068
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	8,621,327		7,933,286	7,197,539
Less allowance for non-acquired loan losses	(53,590)	$ (52,008)	(51,194)	(47,874)	$ (45,203)	$ (43,448)
Loans, net	8,567,737		7,882,092	7,149,665
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	424,584		489,723	556,405
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	2,180,281		2,594,826	3,076,424
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	184,208		207,482	229,502
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,603,364		2,256,996	2,042,125
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	879,724		841,445	906,890
Less allowance for non-acquired loan losses	(5,718)	(5,371)	(5,682)	(6,187)	(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	1,723,640		1,415,551	1,135,235
Less allowance for non-acquired loan losses	(10,311)	(9,740)	(8,754)	(7,209)	(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	27,014		32,942	40,951
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	164,540		196,764	227,739
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	60,391		165,070	281,282
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	595,367		679,253	752,465
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,589,987		1,517,551	1,372,453
Less allowance for non-acquired loan losses	(9,526)	(9,629)	(9,369)	(8,607)	(8,346)	(8,128)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	376,187		421,841	486,254
Consumer loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,594,191		2,431,413	2,190,870
Consumer loans | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	514,242		495,148	456,946
Less allowance for non-acquired loan losses	(3,177)	(3,273)	(3,434)	(3,368)	(3,237)	(3,250)
Consumer loans | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	2,079,949		1,936,265	1,733,924
Less allowance for non-acquired loan losses	(12,432)	(12,058)	(11,913)	(10,945)	(10,193)	(9,668)
Consumer loans | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	208,777		242,425	278,906
Consumer loans | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	577,284		628,813	676,596
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,114,513		1,054,952	941,067
Less allowance for non-acquired loan losses	(7,495)	(7,249)	(7,454)	(6,711)	(6,333)	(5,488)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	10,198		10,043	12,580
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	151,579		212,537	304,864
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	214,203		214,353	205,507
Less allowance for non-acquired loan losses	(1,359)	(1,387)	(1,446)	(1,413)	(1,393)	(1,375)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	111,006		133,110	169,392
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	503,468		448,664	416,650
Less allowance for non-acquired loan losses	(3,572)	(3,195)	(3,101)	(3,071)	(2,899)	(2,788)
Consumer | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	503,468		448,664	416,650
Consumer | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	38,624		42,492	45,633
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	99,690		111,777	126,665
Commercial loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	5,522,067		5,043,852	4,561,152
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	$ 1,601		9,357	28,867
Less allowance for non-acquired loan losses		$ (106)	$ (41)	$ (363)	$ (157)	$ (305)