Leases Schedule of supplemental balance sheet information related to operating leases (Details) $ in Millions	Mar. 31, 2019 USD ($)
Lessor, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 1,008
Operating Lease, Liability, Current	241
Operating Lease, Liability, Noncurrent	823
Operating Lease, Liability	$ 1,064
Operating Lease, Weighted Average Remaining Lease Term	9 years
Operating Lease, Weighted Average Discount Rate, Percent	3.05%
Accounting Standards Update 2016-02 [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Liability	$ 1,064