Loans - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Receivables [Abstract]
Payments for loans in default, number of payments	1	0	1	0
Payments for loans in default	$ 100,000	$ 0	$ 100,000	$ 0
Troubled debt restructuring outstanding amount	14,200,000		14,200,000		$ 15,600,000
Average impaired loans	34,400,000	32,800,000	32,200,000	31,700,000
Interest income recorded on impaired loans	600,000	400,000	900,000	700,000
Interest income related to impaired loans with impairment measured on present value of expected future cash flows	$ 33,000	$ 64,000	$ 121,000	$ 113,000