Acquisitions (Schedule Of Acqusition And Integration Costs) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Acquisition costs			$ 23	$ 45
Integration costs		$ 25	413	191
Acquisition and integration costs	$ 49	25	436	236
CTF Transaction [Member]
Business Acquisition [Line Items]
Acquisition costs			23	44
Integration costs		$ 25	412	152
Connecticut Transaction [Member]
Business Acquisition [Line Items]
Acquisition costs				1
Integration costs			$ 1	$ 39