Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Summary of Significant Accounting Policies (Details 5) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax (benefit) expense										$ (849)	$ 394	$ 438
OPERATING INCOME		$ 524	$ 487	$ 367	$ 631	$ 405	$ 593	$ 647	$ 688	2,009	2,333	2,579
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax (benefit) expense										5
Accounting Standards Update 2016-09 | Restatement adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax										3
Cumulative effect on retained earnings, tax										$ 2
Accounting Standards Update 2017-07 | Restatement adjustment | New accounting pronouncement, early adoption, effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
OPERATING INCOME											$ (2)	$ (26)
Minimum | Accounting Standards Update 2014-09 | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax	$ 400
Maximum | Accounting Standards Update 2014-09 | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax	$ 600