Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	$ 3,964	$ 9,251
OREO	2,662	7,392
Total	6,626	16,643
Level 1
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Total	0	0
Level 2
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Total	0	0
Level 3
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	3,964	9,251
OREO	2,662	7,392
Total	$ 6,626	$ 16,643