Revenue Recognition Contract Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue Recognition [Abstract]
Contract with Customer, Asset, Net - Beginning of Period	$ 25	$ 18	$ 12	$ 8
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress	38	46	83	69
Contract with Customer, Asset, Reclassified to Receivable	(25)	(34)	(57)	(47)
Contract with Customer, Asset, Net - End of Period	$ 38	$ 30	$ 38	$ 30