Income Taxes (Details 4) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets [Abstract]
Net operating loss and other credit carryforwards	$ 44,867	$ 58,129
Compensation and benefits	7,156	9,411
Inventories	322	231
Intangible assets	16,714	34,573
Pension plan	1,760	4,811
Allowance for doubtful accounts	956	971
Deferred revenue	4,953	4,451
Deferred Tax Assets, Equity Method Investments	0	54,686
Foreign tax credit and offset to branch deferreds	56,719	110,052
Other	28,201	46,601
less: valuation allowance	(45,682)	(110,243)
Deferred Tax Assets, Net of Valuation Allowance	115,966	213,673
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(5,074)	(4,709)
Prepaid expenses	(1,447)	(136)
Property, plant and equipment	(108,646)	(223,325)
Equity Investment in partnerships	(24,315)	0
Other	(2,402)	(4,411)
Total deferred tax liabilities	(141,884)	(232,581)
Net deferred tax liabilities	$ (25,918)	$ (18,908)