Leases (Supplemental Cash Flow Information Related to Leases) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 51
Financing cash flows from finance leases	15
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 33