Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	$ (53,842)
Other comprehensive income (loss) before reclassifications	(8,128)
Gains reclassified from accumulated other comprehensive income	2,039
June 30, 2018	(40,849)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	(36,470)
June 30, 2018	(42,559)
Unrealized (Loss) Gain on Investments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	(22)
Other comprehensive income (loss) before reclassifications	150
June 30, 2018	128
Unrealized (Loss) Gain on Derivative Instruments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	(5,219)
Other comprehensive income (loss) before reclassifications	5,786
Gains reclassified from accumulated other comprehensive income	2,039
June 30, 2018	2,606
Unrealized (Loss) Gain on Net Investment Hedge, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	(4,311)
Other comprehensive income (loss) before reclassifications	2,263
June 30, 2018	(2,048)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
December 31, 2017	(26,918)
Other comprehensive income (loss) before reclassifications	(16,327)
June 30, 2018	$ (43,245)