Leases (Contractual Maturities of Operating Lease Liabilities) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
2019	$ 43	[1]
2020	63
2021	55
2022	46
2023	39
Thereafter	182
Total contractual maturities	428
Less imputed interest	(73)
Total operating lease liabilities	$ 355

[1] Contractual maturities for the nine months remaining in 2019.