Loans and Allowance for Loan Losses - Aggregated analysis of the changes in allowance for loan losses - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Changes in allowance for loan losses
Balance at beginning of period	$ 48,075	$ 40,355
Loans charged-off	(1,503)	(1,686)
Recoveries of loans previously charged off	967	732
Net charge-offs	(536)	(954)
Provision for loan losses charged to operations	2,454	3,707
Reduction due to loan removals	(706)	(103)
Balance at end of period	49,287	43,005
Non-acquired loans
Changes in allowance for loan losses
Balance at beginning of period	43,448	36,960
Loans charged-off	(1,169)	(1,297)
Recoveries of loans previously charged off	802	669
Net charge-offs	(367)	(628)
Provision for loan losses charged to operations	2,122	2,117
Balance at end of period	45,203	38,449
Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off	(334)	(389)
Recoveries of loans previously charged off	165	63
Net charge-offs	(169)	(326)
Provision for loan losses charged to operations	169	326
Acquired credit impaired loans
Changes in allowance for loan losses
Balance at beginning of period	4,627	3,395
Provision for loan losses charged to operations	163	1,264
Reduction due to loan removals	(706)	(103)
Balance at end of period	4,084	4,556
Residential real estate | Acquired credit impaired loans
Changes in allowance for loan losses
Reduction due to loan removals	(100)	(63)
Commercial owner occupied real estate loan | Non-acquired loans
Changes in allowance for loan losses
Recoveries of loans previously charged off	8	7
Provision for loan losses charged to operations	210	(135)
Consumer real estate | Acquired credit impaired loans
Changes in allowance for loan losses
Reduction due to loan removals		(6)
Commercial and industrial | Non-acquired loans
Changes in allowance for loan losses
Loans charged-off	(85)	(22)
Recoveries of loans previously charged off	15	90
Provision for loan losses charged to operations	915	214
Commercial and industrial | Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off	(43)	(2)
Recoveries of loans previously charged off	53	1
Provision for loan losses charged to operations	(10)	1
Commercial and industrial | Acquired credit impaired loans
Changes in allowance for loan losses
Reduction due to loan removals	(540)	(30)
Other income producing property | Non-acquired loans
Changes in allowance for loan losses
Recoveries of loans previously charged off	8	43
Provision for loan losses charged to operations	10	(240)
Other income producing property | Acquired non-credit impaired loans
Changes in allowance for loan losses
Recoveries of loans previously charged off		1
Provision for loan losses charged to operations		(1)
Consumer | Non-acquired loans
Changes in allowance for loan losses
Loans charged-off	(979)	(713)
Recoveries of loans previously charged off	203	211
Provision for loan losses charged to operations	887	595
Consumer | Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off	(138)	(74)
Recoveries of loans previously charged off	3	12
Provision for loan losses charged to operations	135	62
Other loans | Non-acquired loans
Changes in allowance for loan losses
Provision for loan losses charged to operations	(148)	(136)
Construction and land development | Commercial non-owner occupied real estate | Non-acquired loans
Changes in allowance for loan losses
Loans charged-off	(35)	(405)
Recoveries of loans previously charged off	442	154
Provision for loan losses charged to operations	(481)	809
Construction and land development | Commercial non-owner occupied real estate | Acquired credit impaired loans
Changes in allowance for loan losses
Reduction due to loan removals	(53)	(6)
Construction and land development | Commercial | Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off	(1)
Recoveries of loans previously charged off	1	1
Provision for loan losses charged to operations		(1)
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Non-acquired loans
Changes in allowance for loan losses
Recoveries of loans previously charged off	2	41
Provision for loan losses charged to operations	271	443
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired credit impaired loans
Changes in allowance for loan losses
Reduction due to loan removals	(13)	2
Home equity loans | Consumer real estate | Non-acquired loans
Changes in allowance for loan losses
Loans charged-off	(66)	(34)
Recoveries of loans previously charged off	101	74
Provision for loan losses charged to operations	(48)	205
Home equity loans | Consumer real estate | Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off	(82)
Recoveries of loans previously charged off	51	9
Provision for loan losses charged to operations	31	(9)
Consumer Owner Occupied Loans | Consumer real estate | Non-acquired loans
Changes in allowance for loan losses
Loans charged-off	(4)	(123)
Recoveries of loans previously charged off	23	49
Provision for loan losses charged to operations	506	362
Consumer Owner Occupied Loans | Consumer real estate | Acquired non-credit impaired loans
Changes in allowance for loan losses
Loans charged-off		(313)
Recoveries of loans previously charged off	57	39
Provision for loan losses charged to operations	$ 13	$ 274