Non Purchased Loans - Restructured Loans (Details) - Non-Purchased $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan
Number of Loans
Beginning balance (loans) | loan	53	59
Additional loans with concessions (loans) | loan	16	15
Reclassified as performing (loans) | loan	2	1
Reclassified as nonperforming (loans) | loan	(7)	(4)
Paid in full (loans) | loan	(8)	(16)
Charge-offs (loans) | loan	(1)	(1)
Transfer to other real estate owned (loans) | loan		(1)
Principal paydowns (loans) | loan	0	0
Lapse of concession period (loans) | loan	(1)
Ending balance (loans) | loan	54	53
Recorded Investment
Beginning balance | $	$ 7,447	$ 10,252
Additional loans with concessions | $	1,453	2,036
Reclassified as performing | $	183	39
Reclassified as nonperforming | $	(853)	(1,406)
Paid in full | $	(1,165)	(2,233)
Charge-offs | $	(250)	(275)
Transfer to other real estate owned | $		(51)
Principal paydowns | $	(304)	(915)
Lapse of concession period | $	(923)
Ending balance | $	$ 5,588	$ 7,447