Loans and Leases - Reserve for Loan and Lease Losses and Recorded Investment in Loans and Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	$ 979		$ 341
Ending balance: collectively evaluated for impairment	18,549		16,103
Ending balance: acquired credit impaired loans evaluated for impairment			8
Total ending balance	19,528	$ 17,499	16,452	$ 17,628
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	42,435		46,474
Ending balance: collectively evaluated for impairment	2,606,486		1,863,631
Loans measured at fair value	2,092
Acquired non-credit impaired loans	684,287		271,884
Acquired credit impaired loans	6,616		1,267
Total Loans and Leases Held for Investment	3,341,916	3,285,886	2,183,256
Commercial, Financial and Agricultural [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	8		151
Ending balance: collectively evaluated for impairment	7,882		5,479
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	7,890	7,037	5,630	6,418
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	9,524		12,977
Ending balance: collectively evaluated for impairment	740,818		473,135
Loans measured at fair value	0
Acquired non-credit impaired loans	90,069		21,207
Acquired credit impaired loans	560		0
Total Loans and Leases Held for Investment	840,971	823,266	507,319
Real Estate-Commercial and Construction [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	26		140
Ending balance: collectively evaluated for impairment	7,598		6,323
Ending balance: acquired credit impaired loans evaluated for impairment			8
Total ending balance	7,624	7,505	6,471	6,572
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	21,658		29,375
Ending balance: collectively evaluated for impairment	1,160,406		821,684
Loans measured at fair value	2,092
Acquired non-credit impaired loans	395,838		122,415
Acquired credit impaired loans	5,261		517
Total Loans and Leases Held for Investment	1,585,255		973,991
Real Estate-Residential Secured for Business Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	364		20
Ending balance: collectively evaluated for impairment	981		727
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	1,345	774	747	763
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	5,178		3,618
Ending balance: collectively evaluated for impairment	175,652		99,973
Loans measured at fair value	0
Acquired non-credit impaired loans	110,820		113,923
Acquired credit impaired loans	582		750
Total Loans and Leases Held for Investment	292,232	294,068	218,264
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	1		30
Ending balance: collectively evaluated for impairment	1,000		1,282
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	1,001	993	1,312	1,575
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	1,054		504
Ending balance: collectively evaluated for impairment	373,852		314,885
Loans measured at fair value	0
Acquired non-credit impaired loans	87,412		14,058
Acquired credit impaired loans	213		0
Total Loans and Leases Held for Investment	462,531		329,447
Loans to Individuals [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	335		356
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	335	364	356	346
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	27,915		28,140
Loans measured at fair value	0
Acquired non-credit impaired loans	148		281
Acquired credit impaired loans	0		0
Total Loans and Leases Held for Investment	28,063	30,373	28,421
Lease Financings [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	580		0
Ending balance: collectively evaluated for impairment	749		922
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	1,329	788	922	1,042
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	5,021		0
Ending balance: collectively evaluated for impairment	127,843		125,814
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	132,864	134,739	125,814
Unallocated Financing Receivables [Member]
Reserve for loan and lease losses:
Ending balance: collectively evaluated for impairment	4		1,014
Ending balance: acquired credit impaired loans evaluated for impairment			0
Total ending balance	$ 4	$ 38	$ 1,014	$ 912