Comprehensive Income (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			$ (10,806)
Other comprehensive loss before reclassifications			(7,761)
Amounts reclassified from accumulated other comprehensive loss			276
Other comprehensive (loss) income	$ 427	$ 112	(7,485)	$ 6,637
Balance at September 30, 2018	(18,291)		(18,291)
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(2,946)
Other comprehensive loss before reclassifications			0
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive (loss) income			0
Balance at September 30, 2018	(2,946)		(2,946)
Unrealized Loss on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(6,666)
Other comprehensive loss before reclassifications			(3,394)
Amounts reclassified from accumulated other comprehensive loss			1,307
Other comprehensive (loss) income			(2,087)
Balance at September 30, 2018	(8,753)		(8,753)
Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			2,158
Other comprehensive loss before reclassifications			(4,367)
Amounts reclassified from accumulated other comprehensive loss			(1,031)
Other comprehensive (loss) income			(5,398)
Balance at September 30, 2018	(3,240)		(3,240)
Other Comprehensive Loss on Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(3,352)
Other comprehensive loss before reclassifications			0
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive (loss) income			0
Balance at September 30, 2018	$ (3,352)		$ (3,352)