Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Excess tax benefits recognized in equity			$ 19
Excess tax benefits included in income taxes in the statement of income	$ 13	$ 26