Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Comprehensive Income
Net income	$ 5,637	$ 8,309	$ 7,482	$ 14,977	$ 13,370
Other comprehensive income (loss):
Adjustment to pension liability	840	1,672	1,760	3,344
Tax expense	(336)	(669)	(704)	(1,338)
Adjustment to pension liability, net of tax	504	1,003	1,056	2,006
Foreign currency translation adjustments	420	(589)	607	(1,719)
Total other comprehensive income, net of tax	924	414	1,663	287
Comprehensive income	6,561	8,723	9,145	15,264
Accumulated other comprehensive income
Balance at beginning of period			(28,118)	(49,734)	(49,734)
Other comprehensive income (loss), net of tax, before reclassifications			607	(1,719)
Amounts reclassified from accumulated other comprehensive income, net of tax			1,056	2,006
Net current period other comprehensive income (loss), net of tax			1,663	287	21,616
Balance at end of period	(26,455)	(49,447)	(26,455)	(49,447)	(28,118)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive income
Balance at beginning of period			(32,279)	(54,431)	(54,431)
Amounts reclassified from accumulated other comprehensive income, net of tax			1,056	2,006
Net current period other comprehensive income (loss), net of tax			1,056	2,006
Balance at end of period	(31,223)	(52,425)	(31,223)	(52,425)
Accumulated Translation Adjustment [Member]
Accumulated other comprehensive income
Balance at beginning of period			4,161	4,697	4,697
Other comprehensive income (loss), net of tax, before reclassifications			607	(1,719)
Net current period other comprehensive income (loss), net of tax			607	(1,719)
Balance at end of period	$ 4,768	$ 2,978	$ 4,768	$ 2,978