Summary of Significant Accounting Policies - Accumulated Other Comprehensive Income and Other Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Rollforward
Beginning of Period			$ 1,861,054
Other comprehensive (loss) income:
Fair value adjustments for interest rate swap agreements	$ (4,931)	$ 2,388	(7,605)	$ 2,203
End of Period	1,657,821		1,657,821
Foreign Currency Translation Adjustments
AOCI Rollforward
Beginning of Period	(247,313)	(73,897)	(264,691)	(103,989)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(5,930)	(135,756)	11,448	(105,664)
Fair value adjustments for interest rate swap agreements	0	0	0	0
Total other comprehensive (loss) income	(5,930)	(135,756)	11,448	(105,664)
End of Period	(253,243)	(209,653)	(253,243)	(209,653)
Fair Value Adjustments for Interest Rate Swap Agreements
AOCI Rollforward
Beginning of Period	(3,647)	(185)	(973)	0
Other comprehensive (loss) income:
Foreign currency translation adjustments	0	0	0	0
Fair value adjustments for interest rate swap agreements	(4,931)	2,388	(7,605)	2,203
Total other comprehensive (loss) income	(4,931)	2,388	(7,605)	2,203
End of Period	(8,578)	2,203	(8,578)	2,203
Total
AOCI Rollforward
Beginning of Period	(250,960)	(74,082)	(265,664)	(103,989)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(5,930)	(135,756)	11,448	(105,664)
Fair value adjustments for interest rate swap agreements	(4,931)	2,388	(7,605)	2,203
Total other comprehensive (loss) income	(10,861)	(133,368)	3,843	(103,461)
End of Period	$ (261,821)	$ (207,450)	$ (261,821)	$ (207,450)

Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to parent entity.

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