Fair Value Measurements, Other Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Financial assets:
Cash and temporary cash investments, at carrying amount	$ 5,207	$ 4,816	$ 4,925	$ 4,114
Financial liabilities:
Debt (excluding capital leases), at carrying amount	7,928	7,926
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and temporary cash investments, at fair value	5,207	4,816
Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Debt (excluding capital leases), at fair value	$ 9,129	$ 8,882