Loans - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) payment	Sep. 30, 2017 USD ($) payment	Sep. 30, 2018 USD ($) payment	Sep. 30, 2017 USD ($) payment	Dec. 31, 2017 USD ($)
Receivables [Abstract]
Payments for loans in default, number of payments | payment	0	0	1	1
Payments for loans in default	$ 0	$ 0	$ 100,000
Troubled debt restructuring outstanding amount	13,800,000		13,800,000		$ 15,600,000
Average impaired loans	38,100,000	30,300,000	34,500,000	$ 31,200,000
Interest income recorded on impaired loans	500,000	400,000	1,400,000	1,100,000
Interest income related to impaired loans with impairment measured on present value of expected future cash flows	$ 36,000	$ 169,000	$ 157,000	$ 282,000