Goodwill And Other Intangible Assets (Schedule Of Change In Goodwill) (Details) - USD ($)		3 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of goodwill and intangible assets		$ 0	$ 0
Goodwill [Roll Forward]
Balance at January 1, 2018		1,614,494,000
Additions	[1]	48,074,000
Other		0
Balance at March 31, 2018		$ 1,662,568,000	$ 1,614,494,000

[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.