Basis of Presentation and Significant Accounting Policies - Cumulative Effect of the Changes from Adoption of Topic 606 (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Other current assets	$ 247,175	$ 241,029	$ 232,027
Other assets	447,816	421,328	241,750
Other current liabilities	144,965	143,699	159,914
Other liabilities	608,156	598,659	661,710
Accumulated other comprehensive loss	(718,169)	(787,119)	(785,189)
Retained earnings	587,483	522,465	$ 252,689
ASU 2014-09 [Member] | Difference between revenue guidance in effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Other current assets	(9,542)	9,002
Other assets	(184,962)	179,578
Other current liabilities	14,038	(16,215)
Other liabilities	68,933	(63,051)
Accumulated other comprehensive loss	(903)	(1,930)
Retained earnings	$ (275,540)	$ 269,776