Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Loans and Allowance for Loan Losses
Loans, net	$ 6,489,068		$ 5,970,044	$ 5,835,646
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	5,008,113		4,220,726	3,994,716
Less allowance for loan losses	(37,319)	$ (36,939)	(34,090)	(35,116)	$ (34,782)	$ (34,539)
Loans, net	4,970,794		4,186,636	3,959,600
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	636,020			773,080
Less allowance for loan losses			(3,706)			(7,365)
Loans, net	632,617		635,411	665,277
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	885,657			1,107,440
Loans, net	885,657		1,041,491	1,099,450
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	268,968			330,754
Less allowance for loan losses			(2,986)			(4,387)
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,192,773		889,756	778,566
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	562,336		401,979	372,077
Less allowance for loan losses	(4,111)	(4,665)	(4,116)	(4,209)	(4,998)	(5,666)
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Total loans	630,437		487,777	406,489
Less allowance for loan losses	(4,591)	(4,656)	(3,568)	(3,324)	(3,038)	(3,154)
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	47,081			55,168
Less allowance for loan losses			(177)			(336)
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	220,489			266,465
Less allowance for loan losses			(56)			(1,444)
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	10,683			16,482
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	35,775			42,172
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,153,480		1,033,398	1,012,428
Less allowance for loan losses	(8,528)	(8,003)	(8,341)	(9,044)	(8,684)	(8,415)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	29,444			42,524
Consumer real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,547,266		1,338,239	1,296,426
Consumer real estate | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	363,825		319,255	308,563
Less allowance for loan losses	(3,281)	(3,148)	(2,929)	(2,911)	(2,868)	(2,829)
Consumer real estate | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	1,864,740		1,617,916	1,571,137
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	1,183,441		1,018,984	987,863
Less allowance for loan losses	(7,850)	(7,530)	(7,212)	(7,455)	(7,125)	(6,866)
Consumer real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	61,866			73,632
Less allowance for loan losses			(313)			(275)
Consumer real estate | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	168,758			203,025
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	435,132			542,278
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	617,525		503,808	462,588
Less allowance for loan losses	(4,710)	(4,269)	(3,974)	(3,976)	(3,983)	(3,561)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	26,658			34,074
Less allowance for loan losses			(174)			(718)
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	14,201			27,459
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	179,595		175,848	169,997
Less allowance for loan losses	(1,619)	(1,812)	(1,963)	(2,027)	(2,019)	(2,232)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	43,152			56,092
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	305,687		233,104	223,210
Less allowance for loan losses	(2,308)	(2,014)	(1,694)	(1,716)	(1,608)	(1,367)
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	148,512			177,408
Commercial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	3,143,373		2,602,810	2,423,579
Single pay loans | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans				24
Less allowance for loan losses						(70)
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	11,787		46,573	51,501
Less allowance for loan losses	(321)	$ (842)	$ (293)	(454)	$ (459)	(449)
Commercial loans 1000000 or more | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	$ 10,958			$ 12,963
Less allowance for loan losses						$ (135)