Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss) (Details)) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax		$ 3,411	$ 0
Beginning Balance		(193,798)	(136,057)
Foreign currency translation adjustment		76,023	(45,426)	$ (55,852)
Unrealized gain on available for sale securities		5,398	0	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax		81,986	(45,991)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax		(600)	587
Net current-period other comprehensive (loss) income, before income taxes		81,386	(45,404)	(52,487)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax		5,398
Income tax expense		(1,974)	(12,337)	(4,322)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax		(1,987)
Net current-period other comprehensive (loss) income, net of income taxes		79,412	(57,741)	(56,809)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax		3,411
Ending Balance		(114,386)	(193,798)	(136,057)
Cash Flow Hedging [Member] | Interest Expense [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	(600)	587
Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive loss		565	(565)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(194,189)	(136,434)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax		0	0
Net current-period other comprehensive (loss) income, before income taxes		76,023	(45,426)
Income tax expense		0	(12,329)
Net current-period other comprehensive (loss) income, net of income taxes		76,023	(57,755)
Ending Balance		(118,166)	(194,189)	(136,434)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		391	377
Net current-period other comprehensive (loss) income, before income taxes		(35)	22
Income tax expense		13	(8)
Net current-period other comprehensive (loss) income, net of income taxes		(22)	14
Ending Balance		$ 369	$ 391	$ 377

[1] There were no gains or losses recognized in earnings related to any ineffective portion of the hedging relationship or related to any amount excluded from the assessment of hedge effectiveness for the years ended December 31, 2017 and 2016.