Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	$ 4,816,875		$ 4,220,726	$ 3,788,399
Less allowance for loan losses	(36,939)	$ (35,115)	(34,090)	(34,782)	$ (33,538)	$ (34,539)
Loans, net	4,779,936		4,186,636	3,753,617
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	662,587			828,670
Less allowance for loan losses			(3,706)			(7,365)
Loans, net	658,835		635,411	710,823
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	941,886			1,171,672
Loans, net	941,886		1,041,491	1,163,613
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	285,518			348,687
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	1,120,047		889,756	720,478
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	533,219		401,979	368,954
Less allowance for loan losses	(4,665)	(4,482)	(4,116)	(4,998)	(5,399)	(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	586,828		487,777	351,524
Less allowance for loan losses	(4,656)	(3,923)	(3,568)	(3,038)	(3,131)	(3,154)
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	48,274			59,819
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	225,460			288,756
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	12,516			17,762
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	36,904			43,123
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,083,051		1,033,398	975,701
Less allowance for loan losses	(8,003)	(8,179)	(8,341)	(8,684)	(7,871)	(8,415)
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	32,267			49,334
Consumer real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,455,624		1,338,239	1,207,047
Consumer real estate | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	345,957		319,255	300,074
Less allowance for loan losses	(3,148)	(3,097)	(2,929)	(2,868)	(2,785)	(2,829)
Consumer real estate | Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	1,820,173		1,617,916	1,480,532
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	1,109,667		1,018,984	906,973
Less allowance for loan losses	(7,530)	(7,345)	(7,212)	(7,125)	(7,041)	(6,866)
Consumer real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	64,114			77,083
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	177,946			210,734
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	466,479			574,697
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	611,901		503,808	448,247
Less allowance for loan losses	(4,269)	(3,951)	(3,974)	(3,983)	(3,460)	(3,561)
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	27,961			38,894
Less allowance for loan losses			(174)			(718)
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	15,598			31,762
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	181,703		175,848	163,441
Less allowance for loan losses	(1,812)	(1,802)	(1,963)	(2,019)	(1,980)	(2,232)
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	44,873			58,987
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	272,957		233,104	209,544
Less allowance for loan losses	(2,014)	(1,785)	(1,694)	(1,608)	(1,422)	(1,367)
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total loans	155,303			185,273
Commercial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,996,702		2,602,810	2,307,867
Single pay loans | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans				58
Less allowance for loan losses						(70)
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	91,592		46,573	63,941
Less allowance for loan losses	(842)	$ (551)	$ (293)	(459)	$ (449)	(449)
Commercial loans 1000000 or more | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total loans	$ 11,260			$ 15,373
Less allowance for loan losses						$ (135)