Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Comprehensive Income
Net income	$ 1,845	$ 6,667	$ 13,370
Other comprehensive income (loss):
Adjustment to pension liability	921	1,672
Tax expense	(368)	(669)
Adjustment to pension liability, net of tax	553	1,003
Foreign currency translation adjustments	186	(1,130)
Total other comprehensive income (loss), net of tax	739	(127)
Comprehensive income	2,584	6,540
Accumulated other comprehensive income
Balance at beginning of period	(28,118)	(49,734)	(49,734)
Other comprehensive income (loss), net of tax, before reclassifications	186	(1,130)
Amounts reclassified from accumulated other comprehensive income, net of tax	553	1,003
Net current period other comprehensive income (loss), net of tax	739	(127)	21,616
Balance at end of period	(27,379)	(49,861)	(28,118)
Defined Benefit Pension Items
Accumulated other comprehensive income
Balance at beginning of period	(32,279)	(54,431)	(54,431)
Other comprehensive income (loss), net of tax, before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income, net of tax	553	1,003
Net current period other comprehensive income (loss), net of tax	553	1,003
Balance at end of period	(31,726)	(53,428)
Foreign Currency Items
Accumulated other comprehensive income
Balance at beginning of period	4,161	4,697	4,697
Other comprehensive income (loss), net of tax, before reclassifications	186	(1,130)
Amounts reclassified from accumulated other comprehensive income, net of tax	0	0
Net current period other comprehensive income (loss), net of tax	186	(1,130)
Balance at end of period	$ 4,347	$ 3,567