Accumulated Other Comprehensive (Loss) Income - Summary of components of accumulated other comprehensive (loss) income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ (10,115)		$ (14,246)
Change during the period
Before-tax amount	(12,039)		6,168
Tax (expense) benefit	3,984		(2,535)
Reclassification adjustment, net of taxes:
Amortization of net loss	337	[1]	498	[1]
Total activity in period	(7,718)		4,131
Balance	(17,833)		(10,115)
Pension Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(9,760)		(14,688)
Change during the period
Before-tax amount	(10,745)		6,976
Tax (expense) benefit	3,922		(2,546)
Reclassification adjustment, net of taxes:
Amortization of net loss	337	[1]	498	[1]
Total activity in period	(6,486)		4,928
Balance	(16,246)		(9,760)
Unrealized Gain (Loss) On Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	10		29
Change during the period
Before-tax amount	(170)		(30)
Tax (expense) benefit	62		11
Reclassification adjustment, net of taxes:
Amortization of net loss		[1]		[1]
Total activity in period	(108)		(19)
Balance	(98)		10
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(365)		413
Change during the period
Before-tax amount	(1,124)		(778)
Tax (expense) benefit
Reclassification adjustment, net of taxes:
Amortization of net loss		[1]		[1]
Total activity in period	(1,124)		(778)
Balance	$ (1,489)		$ (365)

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