Leases - Schedule of Lease (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets	$ 930	$ 1,000
Operating Lease, Current lease liabilities	154
Operating Lease, Long-term lease liabilities	941
Finance Lease, Right-of-use assets	11
Finance Lease, Current lease liabilities	3
Finance Lease, Long-term lease liabilities	24		$ 26
Total Right-of-use assets	941
Total Current lease liabilities	157
Total Long-term lease liabilities	$ 965