Pension Plans and Other Postretirement Benefits Domestic and Foreign Pension and Postretirement Defined Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Total net pension benefits cost	$ 1,389	$ (1,458)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,540	1,979
Interest cost	10,601	9,564
Expected return on assets	(11,309)	(11,082)
Actuarial gain	(50)	0
Amortization of prior service benefit	28	30
Total net pension benefits cost	810	491
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	29	66
Interest cost	621	668
Expected return on assets	(47)	(65)
Amortization of prior service benefit	(24)	(24)
Settlements/curtailments	0	(2,594)	[1]
Total net pension benefits cost	$ 579	$ (1,949)

[1] We assumed responsibility for one domestic OPEB plan in connection with the acquisition of Rockwood which covered a small number of active employees and retirees. This plan was terminated in the first quarter of 2015 and provisions were made for the affected employees and retirees to receive benefits under an existing plan. A gain of $2.6 million was recognized in the first quarter of 2015 related to the termination of this plan.