Accounting Pronouncements Future Minimum Payments Due on Operating Leases (Details) $ in Millions	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Future minimum lease payments	$ 3,435	[1]
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Future minimum lease payments	$ 3,400

[1] Excludes leases having non-cancelable lease terms of less than one year and per diem leases.