Supplemental Financial Information - Other Non-Current Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Other Liabilities, Noncurrent [Abstract]
Postretirement obligation		$ 267	$ 256
Non-current lease-related obligations		104	125
Other deferred compensation		218	204
Other		95	108
Other noncurrent liabilities		708	728
Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Derivative contracts		24	35
Interest rate derivatives | Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Derivative contracts	[1]	$ 24	$ 35

[1] The net amounts of derivative assets and liabilities are reconciled to the individual line item amounts presented in the unaudited Condensed Consolidated Balance Sheet in Note 5.