Fair Value Measurements - OREO Measured at Fair Value on a Nonrecurring Basis (Details) - Level 3 - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
OREO measured at fair value on a nonrecurring basis
Carrying amount prior to remeasurement	$ 1,951	$ 8,732
Impairment recognized in results of operations	(315)	(1,340)
Fair value	$ 1,636	$ 7,392