Stockholders' Equity AOCI (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Components of accumulated other comprehensive loss
Total accumulated other comprehensive loss		$ (47,398)	$ (17,610)	$ (47,398)	$ (17,610)	$ (48,857)	$ (45,565)	$ (18,905)	$ (18,743)
Other comprehensive (loss) income before reclassifications		(378)	1,041	(4,692)	626
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	1,837	254	2,859	507
Net current period other comprehensive income (loss)		1,459	1,295	(1,833)	1,133
Foreign Currency Items
Components of accumulated other comprehensive loss
Foreign currency translation losses		(14,686)	(3,991)	(14,686)	(3,991)	(14,308)	(9,994)	(5,032)	(4,617)
Other comprehensive (loss) income before reclassifications		(378)	1,041	(4,692)	626
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0	0	0	0
Net current period other comprehensive income (loss)		(378)	1,041	(4,692)	626
Defined Benefit Pension and Postretirement Items
Components of accumulated other comprehensive loss
Unrecognized pension and postretirement benefit costs, net of tax		(32,712)	(13,619)	(32,712)	(13,619)	$ (34,549)	$ (35,571)	$ (13,873)	$ (14,126)
Other comprehensive (loss) income before reclassifications		0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	1,837	254	2,859	507
Net current period other comprehensive income (loss)		$ 1,837	$ 254	$ 2,859	$ 507

[1] See reclassifications from accumulated other comprehensive loss table for details of reclassification from accumulated other comprehensive loss for the six months periods ended June 30, 2015 and 2014, respectively.