Accumulated Other Comprehensive (Loss) Income - Summary of components of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		$ (16,702)	$ (18,102)
Change during the period
Before-tax amount		(3,348)	1,129
Tax (expense) benefit		665	(269)
Reclassification adjustment, net of taxes:
Realized loss on securities		0	0
Amortization of net loss	[1]	639	540
Total activity in period		(2,044)	1,400
Balance		(18,746)	(16,702)
Pension Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(14,470)	(15,503)
Change during the period
Before-tax amount		(2,712)	776
Tax (expense) benefit		665	(283)
Reclassification adjustment, net of taxes:
Realized loss on securities		0	0
Amortization of net loss	[1]	639	540
Total activity in period		(1,408)	1,033
Balance		(15,878)	(14,470)
Unrealized Gain (Loss) On Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		15	39
Change during the period
Before-tax amount		(15)	(38)
Tax (expense) benefit		0	14
Reclassification adjustment, net of taxes:
Realized loss on securities		0	0
Amortization of net loss	[1]	0	0
Total activity in period		(15)	(24)
Balance		0	15
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(2,247)	(2,638)
Change during the period
Before-tax amount		(621)	391
Tax (expense) benefit		0	0
Reclassification adjustment, net of taxes:
Realized loss on securities		0	0
Amortization of net loss	[1]	0	0
Total activity in period		(621)	391
Balance		$ (2,868)	$ (2,247)

[1] Reported as part of selling, general and administrative expenses.