Employee Benefit Plans - Changes in Plan Assets and Benefit Obligations in Other Comprehensive Income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total other comprehensive income, net of tax	$ 147	$ 66	$ 134
Post-employment benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain	196	261	293
Amortization of unrecognized net actuarial loss	92	184	269
Amortization of unrecognized prior service cost	(37)	(339)	(338)
Stranded tax effects from the Tax Act and Other	(78)	0	0
Other	47	0	0
Total other comprehensive income, pre-tax	220	106	224
Income tax expense	73	40	90
Total other comprehensive income, net of tax	$ 147	$ 66	$ 134