Loans and Allowance for Loan Losses - Table of loan payment estimates - (Details) - USD ($) $ in Thousands	Jan. 03, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest		$ 774,471		$ 778,822	$ 861,401
Non-accretable difference		(28,966)		(17,502)	(23,294)
Cash flows expected to be collected		745,505		761,320	838,107
Accretable Yield		(139,283)		(155,379)	(175,520)
Carrying value		606,222		605,941	662,587
Allowance for loan losses on acquired loans		(3,741)	$ (4,556)	(3,395)	(3,752)	$ (3,877)	$ (3,706)
Acquired credit impaired loans | SBFC
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest	$ 73,365
Non-accretable difference	(12,912)
Cash flows expected to be collected	60,453
Accretable difference	(4,603)
Carrying value	55,850
Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest	1,010,000
Carrying value	991,500
Fair value adjustment	$ 18,800
Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		1,585,981		836,699	941,886
Residential real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		256,602		258,100	285,518
Allowance for loan losses on acquired loans		(2,741)	(3,108)	(2,419)	(2,592)	(2,863)	(2,986)
Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		322,415		44,718	49,420
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		221,566		27,195	32,267
Consumer real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		56,362		59,300	64,114
Allowance for loan losses on acquired loans		(548)	(589)		(778)	(606)
Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		697,235		569,149	644,425
Commercial and industrial | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		25,486		25,347	27,961
Allowance for loan losses on acquired loans		(320)	(394)	(238)	(196)	(208)	(174)
Commercial and industrial | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		117,884		13,641	15,598
Other income producing property | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		83,403		39,342	44,873
Consumer | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		56,362		59,300	64,114
Allowance for loan losses on acquired loans		(548)		(558)	(778)		(313)
Consumer | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		143,478		142,654	155,303
Commercial | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Allowance for loan losses on acquired loans		(40)		(41)	(35)		(56)
Commercial | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		745,268		124,896	142,158
Commercial loans 1000000 or more | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		8,524		8,617	11,260
Construction and land development | Commercial non-owner occupied real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		52,977		44,373	48,274
Allowance for loan losses on acquired loans		(92)	(130)		(151)	(154)
Construction and land development | Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		112,855		10,090	12,516
Construction and land development | Commercial | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Allowance for loan losses on acquired loans		(92)		(139)	(151)		$ (177)
Other commercial non-owner occupied real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value				210,204
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		206,271		210,204	225,460
Allowance for loan losses on acquired loans		(40)	$ (335)		(35)	$ (46)
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		209,560		34,628	36,904
Home equity loans | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		177,129		160,879	177,946
Consumer | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		143,478		142,654	155,303
Other Consumer | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		840,713		711,803	799,728
Consumer Owner Occupied Loans | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value		$ 520,106		$ 408,270	$ 466,479