Comprehensive Income (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	$ (10,806)
Other comprehensive (loss) income before reclassifications	(4,043)
Amounts reclassified from accumulated other comprehensive loss	6,695
Other comprehensive income (loss)	2,652	$ 4,498	$ (177)
Balance at December 31, 2018	(8,154)	(10,806)
Foreign currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	(2,946)
Other comprehensive (loss) income before reclassifications	0
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive income (loss)	0
Balance at December 31, 2018	(2,946)	(2,946)
Unrealized loss on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	(6,666)
Other comprehensive (loss) income before reclassifications	(1,770)
Amounts reclassified from accumulated other comprehensive loss	5,996
Other comprehensive income (loss)	4,226
Balance at December 31, 2018	(2,440)	(6,666)
Unrealized gain (loss) on derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	2,158
Other comprehensive (loss) income before reclassifications	(3,842)
Amounts reclassified from accumulated other comprehensive loss	699
Other comprehensive income (loss)	(3,143)
Balance at December 31, 2018	(985)	2,158
Other comprehensive loss on pension liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	(3,352)
Other comprehensive (loss) income before reclassifications	1,569
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive income (loss)	1,569
Balance at December 31, 2018	$ (1,783)	$ (3,352)