Leases - Supplemental Balance Sheet Information (Details) $ in Millions	Jun. 30, 2019 USD ($)
Assets
Operating lease assets	$ 1,183
Finance lease assets	150
Total leased assets	1,333
Current
Operating	269
Finance	7
Noncurrent
Operating	962
Finance	155
Total lease liabilities	$ 1,393
Weighted-average remaining lease term (years)
Operating leases	8 years 9 months 18 days
Finance leases	13 years 7 months 6 days
Weighted-average discount rate
Operating leases	6.63%
Finance leases	5.68%