Employee Benefits (Details) - USD ($) $ in Millions					3 Months Ended			12 Months Ended
		Jan. 02, 2016		Dec. 08, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Employee Benefits
Benefit obligation		$ 16,916			$ 16,916		$ 18,872	$ 18,872		$ 17,089		$ 17,089		$ 16,916		$ 18,872	$ 17,089
Defined Benefit Plan, assumed health care cost trend rates
Ultimate health care cost trend rate (as a percent)								4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024	2022
Effect of change of 100 basis points in the assumed initial health care cost trend rate
Effect on the aggregate of the service and interest cost components of net periodic post-retirement benefit expense (statements of operations) - Increase								$ 3
Effect on the aggregate of the service and interest cost components of net periodic post-retirement benefit expense (statements of operations) - Decrease								(3)
Effect of one-percentage point increase on postretirement benefit obligation								73
Effect of one-percentage point decrease on postretirement benefit obligation								$ (68)
Actuarial assumptions at beginning of year:
Ultimate health care cost trend rate (as a percent)								4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024	2022
Components of net periodic benefit (income) expense
Expected return on plan assets								$ (919)		(924)
Settlements							(63)
Actuarial assumptions at end of year:
Ultimate health care cost trend rate (as a percent)								4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024	2022
Change in benefit obligation
Benefit obligation at beginning of year		16,916						$ 18,872		17,089
Benefit obligation at end of year					16,916		18,872	$ 16,916		18,872		17,089
Projected benefit obligation increase due to adoption of new mortality table														$ (379)		$ 1,300
Remaining estimated life of plan participants								8 years
Change in plan assets
Return on plan assets								$ (158)		1,410
Settlements								$ 0		460		0
Pension Plan
Employee Benefits
Amortization period of the plan shortfall								7 years
Unfunded status														2,277		2,471
Employer contributions								$ 100		157		146
Benefits paid by company								6		6		5
Benefits paid from plan assets					356			1,438	[1]	845	[1]	931	[1]
Lump sum pension settlements				$ 460				0		460		0
Termination pension settlement threshold				$ 418
Pension settlement charge										63
Fair value of plan assets		11,072			11,072		12,571	12,571		12,346		12,321		11,072		12,571	$ 12,346
Benefit obligation		13,349			13,349		15,042	$ 15,042		$ 13,401		$ 14,881		13,349		$ 15,042	13,401
Estimated future benefit payments:
2016														1,059
2017														1,010
2018														991
2019														973
2020														954
2021 - 2025														$ 4,433
Actuarial assumptions at beginning of year:
Rate of compensation increase (as a percent)								3.25%		3.25%		3.25%
Expected long-term rate of return on plan assets (as a percent)								7.50%		7.50%		7.50%
Components of net periodic benefit (income) expense
Service cost								$ 83		$ 77		$ 91
Interest cost								568		602		544
Expected return on plan assets								(898)		(891)		(896)
Settlements								0		63		0
Recognition of prior service cost								5		5		5
Recognition of actuarial loss								161		22		84
Net periodic pension benefit income								(81)		(122)		(172)
Actuarial assumptions at end of year:
Rate of compensation increase (as a percent)														3.25%		3.25%
Change in benefit obligation
Benefit obligation at beginning of year		13,349						15,042		13,401		14,881
Service cost								83		77		91
Interest cost								568		602		544
Plan amendments								(100)		4		0
Actuarial loss (gain)								(800)		2,269		(1,179)
Benefits paid by company								6		6		5
Benefits paid from plan assets					356			1,438	[1]	845	[1]	931	[1]
Benefit obligation at end of year					13,349		15,042	13,349		15,042		13,401
Change in plan assets
Fair value of plan assets at beginning of year		11,072						12,571		12,346		12,321
Return on plan assets								(161)		1,373		810
Employer contributions								100		157		146
Benefits paid from plan assets					356			1,438	[1]	845	[1]	931	[1]
Fair value of plan assets at end of year					11,072		12,571	$ 11,072		$ 12,571		$ 12,346
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)								7.50%		7.50%		7.50%
Pension Plan | Interest rate sensitive investments
Target allocation of plan assets
Target asset allocation percentage (as a percent)								45.00%
Pension Plan | Investment grade bonds
Target allocation of plan assets
Target asset allocation percentage (as a percent)								30.00%
Pension Plan | High yield and emerging market bonds
Target allocation of plan assets
Target asset allocation percentage (as a percent)								10.00%
Pension Plan | Diversified strategies
Target allocation of plan assets
Target asset allocation percentage (as a percent)								5.00%
Pension Plan | Interest rate investments with higher returns
Target allocation of plan assets
Target asset allocation percentage (as a percent)								55.00%
Pension Plan | U.S. stocks
Employee Benefits
Fair value of plan assets	[2]	1,201			1,201		1,390	$ 1,390		$ 1,390				$ 1,201		$ 1,390
Change in plan assets
Fair value of plan assets at beginning of year	[2]	1,201						1,390
Fair value of plan assets at end of year	[2]				1,201		1,390	$ 1,201		1,390
Target allocation of plan assets
Target asset allocation percentage (as a percent)								15.00%
Pension Plan | Developed market Non-U.S. stocks
Employee Benefits
Fair value of plan assets	[1]	1,128			1,128		1,170	$ 1,170		1,170				$ 1,128		$ 1,170
Change in plan assets
Fair value of plan assets at beginning of year	[1]	1,128						1,170
Fair value of plan assets at end of year	[1]				1,128		1,170	$ 1,128		$ 1,170
Target allocation of plan assets
Target asset allocation percentage (as a percent)								15.00%
Pension Plan | Diversified multi-asset classes
Target allocation of plan assets
Target asset allocation percentage (as a percent)								7.00%
Pension Plan | Other
Target allocation of plan assets
Target asset allocation percentage (as a percent)								10.00%
Pension Plan | Real estate
Target allocation of plan assets
Target asset allocation percentage (as a percent)								8.00%
Pension Plan | Minimum
Actuarial assumptions at beginning of year:
Discount rate (as a percent)								3.50%		4.20%		3.50%
Actuarial assumptions at end of year:
Discount rate (as a percent)														3.50%		4.20%
Pension Plan | Maximum
Actuarial assumptions at beginning of year:
Discount rate (as a percent)								4.10%		5.10%		4.20%
Actuarial assumptions at end of year:
Discount rate (as a percent)														4.10%		5.10%
Qualified Pension Plan
Employee Benefits
Unfunded status														$ 2,215		$ 2,403
Employer contributions								$ 100
Change in plan assets
Employer contributions								100
Non-qualified Pension Plan
Employee Benefits
Benefits paid by company								6
Estimated future benefit payments:
2016														5
Change in benefit obligation
Benefits paid by company								6
Post-Retirement Benefit Plans
Employee Benefits
Unfunded status														3,374		3,477
Employer contributions								0
Benefits paid by company								181		$ 166		$ 266
Benefits paid from plan assets								163		219		136
Fair value of plan assets		193			193		353	353		535		626		193		353	535
Benefits paid, net of participant contributions and direct subsidy receipts								116
Benefit obligation		3,567			3,567		3,830	$ 3,830		$ 3,688		$ 4,075		$ 3,567		$ 3,830	$ 3,688
Defined Benefit Plan, assumed health care cost trend rates
Decrease in health care cost trend rate per year								decrease between 0.05% to 0.10% per year
Health care cost trend rate (as a percent)								5.00%
Ultimate health care cost trend rate (as a percent)								4.50%		4.50%		4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024
Estimated future benefit payments:
2016														$ 309
2017														300
2018														290
2019														283
2020														276
2021 - 2025														1,256
Medicare Part D Subsidy Receipts
2016														(7)
2017														(7)
2018														(7)
2019														(7)
2020														(7)
2021 - 2025														$ (30)
Actuarial assumptions at beginning of year:
Discount rate (as a percent)								3.80%		4.50%
Expected long-term rate of return on plan assets (as a percent)								7.50%
Ultimate health care cost trend rate (as a percent)								4.50%		4.50%		4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024
Components of net periodic benefit (income) expense
Service cost								$ 24		$ 22		$ 24
Interest cost								140		159		140
Expected return on plan assets								(21)		(33)		(39)
Recognition of prior service cost								19		20		0
Recognition of actuarial loss								0		0		4
Net periodic pension benefit income								$ 162		$ 168		$ 129
Actuarial assumptions at end of year:
Discount rate (as a percent)														4.15%		3.80%
Initial health care cost trend rate (as a percent)												6.50%
Ultimate health care cost trend rate (as a percent)								4.50%		4.50%		4.50%
Year that health care cost rate reaches ultimate trend rate														2025		2024
Change in benefit obligation
Benefit obligation at beginning of year		3,567						$ 3,830		$ 3,688		$ 4,075
Service cost								24		22		24
Interest cost								140		159		140
Participant contributions								57		69		96
Plan amendments								0		23		141
Direct subsidy receipts								8		9		13
Actuarial loss (gain)								(148)		245		(399)
Benefits paid by company								181		166		266
Benefits paid from plan assets								163		219		136
Benefit obligation at end of year					3,567		3,830	3,567		3,830		3,688
Change in plan assets
Fair value of plan assets at beginning of year		193						353		535		626
Return on plan assets								3		37		45
Employer contributions								0
Benefits paid from plan assets								163		219		136
Fair value of plan assets at end of year					193		353	$ 193		353		$ 535
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)								7.50%
Post-Retirement Benefit Plans | U.S. stocks
Employee Benefits
Fair value of plan assets		16	[2]		16	[2]	35	$ 35		35				$ 16	[2]	$ 35
Change in plan assets
Fair value of plan assets at beginning of year		16	[2]					35
Fair value of plan assets at end of year					16	[2]	35	16	[2]	35
Post-Retirement Benefit Plans | Developed market Non-U.S. stocks
Employee Benefits
Fair value of plan assets		12	[1]		12	[1]	33	33		33				$ 12	[1]	$ 33
Change in plan assets
Fair value of plan assets at beginning of year		$ 12	[1]					33
Fair value of plan assets at end of year					$ 12	[1]	$ 33	$ 12	[1]	$ 33
Post-Retirement Benefit Plans | Equity Securities
Target allocation of plan assets
Target asset allocation percentage (as a percent)								20.00%
Post-Retirement Benefit Plans | Non-equity investments
Target allocation of plan assets
Target asset allocation percentage (as a percent)								80.00%
Post-Retirement Benefit Plans | Minimum
Actuarial assumptions at beginning of year:
Discount rate (as a percent)												3.60%
Expected long-term rate of return on plan assets (as a percent)										6.00%		6.00%
Actuarial assumptions at end of year:
Initial health care cost trend rate (as a percent)								5.00%		6.00%
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)										6.00%		6.00%
Post-Retirement Benefit Plans | Maximum
Actuarial assumptions at beginning of year:
Discount rate (as a percent)
Expected long-term rate of return on plan assets (as a percent)										7.50%		7.30%
Actuarial assumptions at end of year:
Initial health care cost trend rate (as a percent)								5.25%		6.50%
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)										7.50%		7.30%
Scenario, Forecast [Member] | Pension Plan
Actuarial assumptions at beginning of year:
Expected long-term rate of return on plan assets (as a percent)		7.50%
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)		7.50%
Expected long-term return on assets, net of administrative expenses		7.00%
Scenario, Forecast [Member] | Post-Retirement Benefit Plans
Employee Benefits
Benefits paid, net of participant contributions and direct subsidy receipts		$ 137
Actuarial assumptions at beginning of year:
Expected long-term rate of return on plan assets (as a percent)		7.00%
Target allocation of plan assets
Expected long-term rate of return on plan assets (as a percent)		7.00%

[1] Non-U.S. stocks represent investments in stocks of companies based in developed countries outside the U.S. as well as commingled funds. The valuation inputs for non-U.S. stocks are based on the last published price reported on the major stock market on which the securities are traded and are primarily classified as Level 1. The commingled funds are valued at NAV based on the market value of the underlying investments using the same valuation inputs described above.

[2] U.S. stocks represent investments in stocks of U.S. based companies as well as commingled U.S. stock funds. The valuation inputs for U.S. stocks are based on the last published price reported on the major stock market on which the securities are traded and are classified as Level 1. The commingled funds are valued at NAV based on the market value of the underlying investments using the same valuation inputs described above.