New Accounting Pronouncements - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2019	Apr. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 7,054	$ 7,358
Operating Lease, Liability, Current	1,680	1,813
Operating Lease, Liability, Noncurrent	5,913	6,263
Finance lease, right-of-use asset	$ 612	613
Accumulated Deficit [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		104
Liability [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		108
Property, Plant and Equipment [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 4