Basis of Presentation and Significant Accounting Policies - Cumulative Effect of the Changes from Adoption of Topic 606 (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Other current assets	$ 258,685	$ 241,029	$ 232,027
Other assets	562,332	421,328	241,750
Other current liabilities	123,824	143,699	159,914
Other liabilities	634,060	598,659	661,710
Accumulated other comprehensive loss	(922,148)	(787,119)	(785,189)
Retained earnings	779,926	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	(9,358)	9,002
Other assets	(190,276)	179,578
Other current liabilities	18,636	(16,215)
Other liabilities	67,996	(63,051)
Accumulated other comprehensive loss	7,056	(1,930)
Retained earnings	$ (290,212)	$ 269,776