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	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Accumulated goodwill impairment charges			$ 3,429,000,000							$ 9,154,000,000	$ 3,429,000,000
Estimated future amortization expense, year 1										343,000,000
Estimated future amortization expense, year 2										253,000,000
Estimated future amortization expense, year 3										170,000,000
Estimated future amortization expense, year 4										95,000,000
Estimated future amortization expense, year 5										26,000,000
Goodwill Impairment										5,725,000,000	641,000,000	$ 2,748,000,000
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%	5.50%	5.50%	5.80%	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										4 years 4 months 24 days
Transfer of gross intangible assets to held for sale										$ 856,000,000
Transfer of net intangible assets to held for sale										$ 30,000,000
Royalty Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Asset, Weighted-Average Period before Renewal or Extension										1 year 3 months 18 days