Derivative Instruments (Hedges of Net Investments in Foreign Operations) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives	[1],[2]	$ 31,431	$ (37,567)	$ (10,234)
Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives	[1],[2]	$ 55,913	$ (10,386)	$ 0

[1] There was no ineffectiveness recognized for the Company’s hedges of net investments in foreign operations.

[2] There were no sales or substantial liquidations of net investments in foreign operations that would have required the reclassification of gains or losses from accumulated other comprehensive income (loss) into investment income during the periods presented.