Employee Benefits Schedule of Defined Benefit Plan Disclosures (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair value of plan assets:
Benefit payments	$ (16)
As of January 1		$ 550	$ 591
Classification in consolidated balance sheet:
Noncurrent asset		(33)	(32)
Noncurrent liability		(259)	(237)
Pension Plans, Defined Benefit [Member]
Benefit obligation:
As of January 1		758	777	$ 705
Fair value of plan assets:
Service cost		18	15	17
Interest cost on benefit obligation		31	34	30
Participants’ contributions		0	0
Actuarial loss (gain)		(31)	72
Defined Benefit Plan, Special Termination Benefits		0	0
Benefit payments		(35)	(48)
Defined Benefit Plan, Administration Expenses		(2)	(1)
As of January 1		550	591	596
Unfunded position as of December 31		208	186
Net actuarial loss (gain) included in comprehensive income		13	67
Defined Benefit Plan, Amortization of Gains (Losses)		(20)	(17)	(24)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0	0	0
Total Amounts included in comprehensive income		(7)	50
Defined Benefit Plan, Accumulated Benefit Obligation		681	691
Actual return on plan assets		(4)	44
Company contributions		0	0
Classification in consolidated balance sheet:
Noncurrent asset		0	0
Current liability		0	0
Noncurrent liability		(208)	(186)
Amounts included in AOCL:
Net actuarial loss		228	236
Prior service cost		0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		$ 228	$ 236
Assumptions used:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Obligation, Discount Rate		4.36%	4.02%
Discount rate used to calculate benefit obligation		4.02%	4.84%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Obligation, Rate of Compensation Increase		3.65%	3.65%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase		3.65%	3.65%
Long-term rate of return on plan assets		7.50%	7.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		7.50%	7.50%
Other Postretirement Benefit Plans [Member]
Benefit obligation:
As of January 1		$ 81	$ 83	77
Fair value of plan assets:
Service cost		2	2	2
Interest cost on benefit obligation		3	4	3
Participants’ contributions		2	1
Actuarial loss (gain)		(4)	4
Defined Benefit Plan, Special Termination Benefits		1	1
Benefit payments		(6)	(6)
Defined Benefit Plan, Administration Expenses		0	0
As of January 1		30	32	32
Unfunded position as of December 31		51	51
Net actuarial loss (gain) included in comprehensive income		0	5
Defined Benefit Plan, Amortization of Gains (Losses)		(1)	(1)	(1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		(1)	(1)	(1)
Total Amounts included in comprehensive income		(2)	3
Actual return on plan assets		(2)	1
Company contributions		4	4
Classification in consolidated balance sheet:
Noncurrent asset		0	0
Current liability		0	0
Noncurrent liability		(51)	(51)
Amounts included in AOCL:
Net actuarial loss		9	10
Prior service cost		1	1
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		$ 10	$ 11
Assumptions used:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Obligation, Discount Rate		3.90%	3.07%
Defined Benefit Plan Discount rate - upper range		4.45%	4.10%
Discount rate used to calculate benefit obligation		3.07%	3.46%
Defined Benefit Plan Cost Discount rate - upper range		4.10%	4.96%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Obligation, Rate of Compensation Increase		4.58%	4.58%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase		4.58%	4.58%
Long-term rate of return on plan assets		6.29%	6.37%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		6.37%	6.46%
Non Qualified Benefit Plans [Member]
Benefit obligation:
As of January 1		$ 27	$ 27	24
Fair value of plan assets:
Service cost		0	0	0
Interest cost on benefit obligation		1	1	1
Participants’ contributions		0	0
Actuarial loss (gain)		1	5
Defined Benefit Plan, Special Termination Benefits		0	0
Benefit payments		(2)	(3)
Defined Benefit Plan, Administration Expenses		0	0
As of January 1		15	15	16
Unfunded position as of December 31		12	12
Net actuarial loss (gain) included in comprehensive income		1	5
Defined Benefit Plan, Amortization of Gains (Losses)		(1)	(1)	(1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0	0	$ 0
Total Amounts included in comprehensive income		0	4
Defined Benefit Plan, Accumulated Benefit Obligation		27	27
Actual return on plan assets		0	1
Company contributions		2	1
Classification in consolidated balance sheet:
Noncurrent asset		(15)	(15)
Current liability		(2)	(2)
Noncurrent liability		(25)	(25)
Amounts included in AOCL:
Net actuarial loss		13	13
Prior service cost		0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		$ 13	$ 13
Assumptions used:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Obligation, Discount Rate		4.36%	4.02%
Discount rate used to calculate benefit obligation		4.02%	4.84%