Goodwill And Other Intangible Assets (Schedule Of Change In Goodwill) (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2018 USD ($) reporting_unit	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of goodwill and intangible assets			$ 0
Number of reporting units | reporting_unit		1
Goodwill [Roll Forward]
Balance at January 1, 2018				$ 1,614,494,000
Additions	[1]			46,770,000
Other				0
Balance at September 30, 2018		$ 1,661,264,000	$ 1,614,494,000	$ 1,661,264,000

[1] Amount relates to preliminary purchase price allocation of goodwill associated with the 2018 Business Combination. See Note 5 for more information regarding the Company's acquisitions.