Fair Value Measurements, Other Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financial assets:
Cash and temporary cash investments, at carrying amount	$ 4,114	$ 3,689	$ 4,292	$ 1,723
Financial liabilities:
Debt (excluding capital leases), at carrying amount	7,292	6,354
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and temporary cash investments, at fair value	4,114	3,689
Fair Value, Inputs, Level 2 [Member]
Financial liabilities:
Debt (excluding capital leases), at fair value	$ 7,759	$ 7,562