Loans and Leases - Reserve for Loan and Lease Losses and Recorded Investment in Loans and Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	$ 1,017			$ 410
Ending balance: collectively evaluated for impairment	19,893			16,743
Total ending balance	20,910	$ 19,528	$ 17,499	17,153	$ 16,452	$ 17,628
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	41,713			44,034
Ending balance: collectively evaluated for impairment	2,814,256			2,044,187
Loans measured at fair value	2,058
Acquired non-credit impaired loans	645,658			255,874
Acquired credit impaired loans	6,485			942
Total Loans and Leases Held for Investment	3,510,170		3,285,886	2,345,037
Commercial, Financial and Agricultural [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	10			390
Ending balance: collectively evaluated for impairment	8,303			5,398
Total ending balance	8,313	7,890	7,037	5,788	5,630	6,418
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	9,794			12,472
Ending balance: collectively evaluated for impairment	809,693			546,892
Loans measured at fair value	0
Acquired non-credit impaired loans	85,178			20,096
Acquired credit impaired loans	502			0
Total Loans and Leases Held for Investment	905,167		823,266	579,460
Real Estate-Commercial and Construction [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	59			4
Ending balance: collectively evaluated for impairment	8,409			7,545
Total ending balance	8,468	7,624	7,505	7,549	6,471	6,572
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	20,735			26,761
Ending balance: collectively evaluated for impairment	1,268,132			885,131
Loans measured at fair value	2,058
Acquired non-credit impaired loans	378,413			114,965
Acquired credit impaired loans	5,185			180
Total Loans and Leases Held for Investment	1,674,523			1,027,037
Real Estate-Residential Secured for Business Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	37			16
Ending balance: collectively evaluated for impairment	1,092			40
Total ending balance	1,129	1,345	774	56	747	763
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	5,196			3,772
Ending balance: collectively evaluated for impairment	189,173			118,601
Loans measured at fair value	0
Acquired non-credit impaired loans	99,151			107,087
Acquired credit impaired loans	583			762
Total Loans and Leases Held for Investment	294,103		294,068	230,222
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	25			0
Ending balance: collectively evaluated for impairment	949			1,301
Total ending balance	974	1,001	993	1,301	1,312	1,575
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	967			1,029
Ending balance: collectively evaluated for impairment	394,683			333,887
Loans measured at fair value	0
Acquired non-credit impaired loans	82,770			13,420
Acquired credit impaired loans	215			0
Total Loans and Leases Held for Investment	478,635			348,336
Loans to Individuals [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	0			0
Ending balance: collectively evaluated for impairment	329			411
Total ending balance	329	335	364	411	356	346
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	0			0
Ending balance: collectively evaluated for impairment	27,442			30,880
Loans measured at fair value	0
Acquired non-credit impaired loans	146			306
Acquired credit impaired loans	0			0
Total Loans and Leases Held for Investment	27,588		30,373	31,186
Lease Financings [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	886			0
Ending balance: collectively evaluated for impairment	774			1,121
Total ending balance	1,660	1,329	788	1,121	922	1,042
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	5,021			0
Ending balance: collectively evaluated for impairment	125,133			128,796
Loans measured at fair value	0
Acquired non-credit impaired loans	0			0
Acquired credit impaired loans	0			0
Total Loans and Leases Held for Investment	130,154		134,739	128,796
Unallocated Financing Receivables [Member]
Reserve for loan and lease losses:
Ending balance: collectively evaluated for impairment	37			927
Total ending balance	$ 37	$ 4	$ 38	$ 927	$ 1,014	$ 912