Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in the balances of each component of AOCI
Balance at the beginning of the period	$ 714,615	$ 738,932	$ 780,230
Other comprehensive income (loss), net of tax	429	(121)	(3,152)
Balance at the end of the period	594,595	714,615	738,932
Accumulated Other Comprehensive Income
Changes in the balances of each component of AOCI
Balance at the beginning of the period	1,348	1,469	4,621
Other comprehensive income (loss) before reclassifications	(25)		55
Amounts reclassified from AOCI	454		(3,207)
Other comprehensive income (loss), net of tax	429	(121)	(3,152)
Balance at the end of the period	1,777	1,348	1,469
Foreign Currency Translation
Changes in the balances of each component of AOCI
Balance at the beginning of the period	2,246	2,333	5,326
Other comprehensive income (loss) before reclassifications	(19)		149
Amounts reclassified from AOCI	(430)		(3,142)
Other comprehensive income (loss), net of tax	(449)	(87)	(2,993)
Balance at the end of the period	1,797	2,246	2,333
Foreign Currency Translation | ALD | Other net
Changes in the balances of each component of AOCI
Amounts reclassified from AOCI	400
Foreign Currency Translation | ALD | Accumulated Other Comprehensive Income
Changes in the balances of each component of AOCI
Amounts reclassified from AOCI	(400)
Minimum Pension Liability
Changes in the balances of each component of AOCI
Balance at the beginning of the period	(866)	(881)	(736)
Other comprehensive income (loss) before reclassifications			(145)
Amounts reclassified from AOCI	866
Other comprehensive income (loss), net of tax	866	15	(145)
Balance at the end of the period		(866)	(881)
Minimum Pension Liability | Other net
Changes in the balances of each component of AOCI
Amounts reclassified from AOCI	900
Tax benefit related to amounts reclassified from AOCI	400
Minimum Pension Liability | Accumulated Other Comprehensive Income
Changes in the balances of each component of AOCI
Amounts reclassified from AOCI	(900)
Tax benefit related to amounts reclassified from AOCI	(400)
Unrealized Gains (Losses) on Available for Sale Securities
Changes in the balances of each component of AOCI
Balance at the beginning of the period	(32)	17	31
Other comprehensive income (loss) before reclassifications	(6)		51
Amounts reclassified from AOCI	18		(65)
Other comprehensive income (loss), net of tax	12	(49)	(14)
Balance at the end of the period	$ (20)	$ (32)	$ 17