Fair Value of Financial Instruments - Assets Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Level 1
Assets:
Loans held for sale	$ 0	$ 0
Level 2
Assets:
Loans held for sale	1,792	1,639
Level 3
Assets:
Loans held for sale	0	0
Fair Value, Measurements, Nonrecurring
Assets:
Loans held for sale	1,792	1,639
Impaired loans, net of valuation allowance	420	1,391
Other real estate owned, net	1,716	1,225
Fair Value, Measurements, Nonrecurring | Level 1
Assets:
Loans held for sale	0	0
Impaired loans, net of valuation allowance	0	0
Other real estate owned, net	0	0
Fair Value, Measurements, Nonrecurring | Level 2
Assets:
Loans held for sale	1,792	1,639
Impaired loans, net of valuation allowance	0	0
Other real estate owned, net	0	0
Fair Value, Measurements, Nonrecurring | Level 3
Assets:
Loans held for sale	0	0
Impaired loans, net of valuation allowance	420	1,391
Other real estate owned, net	$ 1,716	$ 1,225