Acquisition (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended								8 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2019	Apr. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Revenues	$ 4,344	$ 4,638	$ 4,310	$ 3,965	$ 4,531	$ 4,264	$ 4,020	$ 3,609		$ 17,258		$ 16,424	$ 14,257
Net income (loss)	$ 431	$ (161)	$ 363	$ 252	$ 399	$ 490	$ 385	$ 367		$ 886		$ 1,641	$ 2,079
Liberty Transaction [Member]
Business Acquisition [Line Items]
Acquisition agreement date										May 01, 2018
Capital stock acquired, percent					100.00%				100.00%			100.00%
Acquisition related costs												$ 85
Provisional assets											$ (5)
Provisional liabilities											23
Provisional goodwill											$ 28
Revenues									$ 1,500
Net income (loss)									$ 36