Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	$ 14,207	$ 9,251
OREO	4,162	7,392
Total financial assets	18,369	16,643
Level 1
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Total financial assets	0	0
Level 2
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Total financial assets	0	0
Level 3
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	14,207	9,251
OREO	4,162	7,392
Total financial assets	$ 18,369	$ 16,643