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		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative [Line Items]
Weighted average of U.S. dollar equivalent of foreign denominated net assets		$ 2,394,185	$ 1,815,593	$ 2,314,466	$ 1,222,267
Derivative gains (losses)	[1]	$ 45,397	$ (30,498)	$ 33,882	$ 36,272

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