Lease Obligations - Lessee - Other Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease obligations other information [Line Items]
Operating lease weighted average discount rate, percent	3.15%
Finance lease weighted average discount rate, percent	4.06%
Operating lease weighted average remaining lease term	9 years 5 months 15 days
Finance lease weighted average remaining lease term	15 years 11 months 1 day
Lease liability
Lease obligations other information [Line Items]
Operating cash flows from operating leases	$ 24	$ 21
Financing cash flows from finance leases	$ 1	$ 1