Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Fair value measurements
Fair value carrying amount		$ 8,626	$ 13,123
Mortgages held for sale reported at fair value
Fair value measurements
Fair value carrying amount		8,626	13,123
Aggregate unpaid principal		8,611	12,967
Excess of fair value carrying amount over (under) unpaid principal	[1]	$ 15	$ 156

[1] The excess of fair value carrying amount over (under) unpaid principal is included in mortgage banking income and includes changes in fair value at and subsequent to funding and gains and losses on the related loan commitment prior to funding.