Derivative Instruments - Derivative instruments designated as hedges of the net investment in a foreign operation - Summary (Details) - Derivatives designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Derivative [Line Items]
Weighted average of U.S. dollar equivalent of foreign denominated net assets	$ 1,167,395	$ 2,575,987	$ 1,501,284		$ 2,401,640
Derivative gains (losses)	$ (15,280)	$ 1,999	$ (94,047)	[1]	$ 35,882	[1]

[1] Derivative gains (losses) from derivative instruments designated as hedges of an investment in a foreign operation are recorded in the cumulative translation adjustment account within AOCI for each period.