Leases - Supplemental Balance Sheet (Details) $ in Millions	Jun. 30, 2019 USD ($)
Assets
Operating lease assets	$ 1,844
Finance lease assets	263
Total leased assets	2,107
Current
Operating	488
Finance	32
Noncurrent
Operating	1,467
Finance	188
Total lease liabilities	$ 2,175
Weighted-average remaining lease term (years)
Operating leases	7 years 9 months 18 days
Finance leases	11 years 2 months 12 days
Weighted-average discount rate
Operating leases	6.96%
Finance leases	5.46%