Stock-Based and Other Compensation Plans Stock-Based and Other Compensation Plans (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, recognized net gain due to curtailments	$ 21
Defined benefit plan, curtailments	$ 20
Defined benefit plan, eligibility period threshold	10 years
Noncurrent Liabilities	$ (25)	$ (24)
Net Prior Service (Cost) Credit, Before Tax	(88)
Accumulated Other Comprehensive Income (Loss)	(33)	(90)	$ (117)	$ (113)
Net periodic benefit cost	16	11	$ 37
Retirement and Restoration Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension or Other Benefit Obligation	(24)	(363)
Fair Value of Plan Assets	0	242
Net Amount Recognized in Consolidated Balance Sheet	(24)	(121)
Current Liabilities	(2)	(102)
Noncurrent Liabilities	(22)	(19)
Net Prior Service (Cost) Credit, Before Tax	(15)	(75)
Net Gains (Losses), Before Tax	4	42
Accumulated Other Comprehensive Income (Loss)	(19)	(117)
Medical and Life Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension or Other Benefit Obligation	(5)	(7)
Fair Value of Plan Assets	0	0
Net Amount Recognized in Consolidated Balance Sheet	(5)	(7)
Current Liabilities	(1)	(2)
Noncurrent Liabilities	(4)	(5)
Net Prior Service (Cost) Credit, Before Tax	2	2
Net Gains (Losses), Before Tax	0	0
Accumulated Other Comprehensive Income (Loss)	$ 2	$ 2