Accumulated Other Comprehensive (Loss) Income - Summary of components of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income Loss [Roll Forward]
Balance		$ (17,969)	$ (17,833)
Change during the period
Before-tax amount		(1,382)	(196)
Tax (expense) benefit		742	(586)
Reclassification adjustment, net of taxes:
Realized loss on securities			144
Amortization of net loss	[1]	507	502
Total activity in period		(133)	(136)
Balance		(18,102)	(17,969)
Pension Adjustment
Accumulated Other Comprehensive Income Loss [Roll Forward]
Balance		(14,715)	(16,246)
Change during the period
Before-tax amount		(2,039)	1,621
Tax (expense) benefit		744	(592)
Reclassification adjustment, net of taxes:
Realized loss on securities
Amortization of net loss	[1]	507	502
Total activity in period		(788)	1,531
Balance		(15,503)	(14,715)
Unrealized Gain (Loss) On Securities
Accumulated Other Comprehensive Income Loss [Roll Forward]
Balance		36	(98)
Change during the period
Before-tax amount		5	(16)
Tax (expense) benefit		(2)	6
Reclassification adjustment, net of taxes:
Realized loss on securities			144
Amortization of net loss	[1]
Total activity in period		3	134
Balance		39	36
Foreign Currency Translation
Accumulated Other Comprehensive Income Loss [Roll Forward]
Balance		(3,290)	(1,489)
Change during the period
Before-tax amount		652	(1,801)
Tax (expense) benefit
Reclassification adjustment, net of taxes:
Realized loss on securities
Amortization of net loss	[1]
Total activity in period		652	(1,801)
Balance		$ (2,638)	$ (3,290)

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