Goodwill And Other Intangibles (Narrative) (Details) - USD ($)	3 Months Ended					9 Months Ended	12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Accumulated goodwill impairment charges							$ 9,154,000,000	$ 9,154,000,000
Estimated future amortization expense, year 1							253,000,000
Estimated future amortization expense, year 2							170,000,000
Estimated future amortization expense, year 3							95,000,000
Estimated future amortization expense, year 4							26,000,000
Estimated future amortization expense, year 5							7,000,000
Goodwill associated with planned disposal								658,000,000
Goodwill impairment								5,725,000,000	$ 641,000,000
Infinite-lived intangible impairment							$ 0	$ 0	$ 0
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life							8 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life							12 years
Measurement Input, EBITDA Multiple [Member]
Finite-Lived Intangible Assets [Line Items]
EBITDA multiplier	4.40%	4.40%	5.30%	5.50%	5.50%	5.50%		4.40%
Measurement Input, EBITDA Multiple [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
EBITDA multiplier							4.40%
Measurement Input, EBITDA Multiple [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
EBITDA multiplier							6.50%
Customer Base [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Asset, Weighted-Average Period before Renewal or Extension							3 years 6 months
Royalty Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Asset, Weighted-Average Period before Renewal or Extension							3 months 18 days