Leases - Activities Associated With Operating Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Fixed lease expenses	$ 37
Variable lease expenses	29
Total lease expenses	66
Cash paid for leases	67
ROU assets obtained in exchange for lease obligations	42
Reduction of ROU assets and lease liabilities	(16)
Net non-cash increases to ROU assets and lease liabilities	$ 26