Comprehensive Income (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2016	$ (28,704)
Other comprehensive income (loss) before reclassifications	5,529
Amounts reclassified from accumulated other comprehensive loss	(1,031)
Other comprehensive income (loss)	4,498	$ (177)	$ 8,263
Distribution of the GoTo Business	13,400
Balance at December 31, 2017	(10,806)	(28,704)
Foreign currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2016	(16,346)
Other comprehensive income (loss) before reclassifications	0
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive income (loss)	0
Distribution of the GoTo Business	13,400
Balance at December 31, 2017	(2,946)	(16,346)
Unrealized loss on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2016	(3,108)
Other comprehensive income (loss) before reclassifications	(3,285)
Amounts reclassified from accumulated other comprehensive loss	(273)
Other comprehensive income (loss)	(3,558)
Distribution of the GoTo Business	0
Balance at December 31, 2017	(6,666)	(3,108)
Unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2016	(3,130)
Other comprehensive income (loss) before reclassifications	6,046
Amounts reclassified from accumulated other comprehensive loss	(758)
Other comprehensive income (loss)	5,288
Distribution of the GoTo Business	0
Balance at December 31, 2017	2,158	(3,130)
Other comprehensive loss on pension liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2016	(6,120)
Other comprehensive income (loss) before reclassifications	2,768
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive income (loss)	2,768
Distribution of the GoTo Business	0
Balance at December 31, 2017	$ (3,352)	$ (6,120)