Goodwill And Other Intangible Assets (Schedule Of Change In Goodwill) (Details)		3 Months Ended			6 Months Ended
		Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) reporting_unit	Dec. 31, 2016 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Statement [Line Items]
Impairment of goodwill and intangible assets		$ 0		$ 0
Number of reporting units | reporting_unit			2
Goodwill distributed to GetGo		1,617,105,000	$ 1,585,893,000	1,585,893,000	$ 1,585,893,000	$ 1,585,893,000
Goodwill [Roll Forward]
Balance at January 1, 2017			$ 1,585,893,000		1,585,893,000
Additions	[1]				31,212,000
Other					0
Balance at June 30, 2017		$ 1,617,105,000		$ 1,585,893,000	$ 1,617,105,000
GoTo Business Division [Member]
Statement [Line Items]
Goodwill attributable to the GoTo Business						$ 380,917,000

[1] Amount relates to preliminary purchase price allocation of goodwill associated with the 2017 Business Combination. See Note 5 for more information regarding the Company's acquisitions.