Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 52,826	$ 67,794
Other comprehensive income (loss) before reclassifications	(1,846)	385
Less: amounts reclassified from accumulated other comprehensive income (loss)	0	51
Cumulative effect of adoption of ASU No. 2018-02, net of taxes	0
Net current period other comprehensive income (loss)	(2,325)	334
Balance at end of period	51,424	66,573
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(363)	(1,080)
Cumulative effect of adoption of ASU No. 2018-02, net of taxes	(77)
Balance at end of period	$ (2,688)	$ (746)
Accounting Standards Update 2016-01
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes				$ 0
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			$ (1,100)	$ (556)	$ 0