Retirement Plans - Change in the projected benefit obligation and in the fair value of plan assets (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Pension Benefits
Change in projected benefit obligation
Projected benefit obligation at beginning of year	$ 8,563	$ 7,991
Service cost	104	100	$ 98
Interest cost	306	323	338
Actuarial (gains) losses	(615)	494
Benefits paid	(422)	(413)
Plan amendment	20	1
Business Disposition	15
Foreign exchange rate changes and other	(40)	67
Projected benefit obligation at end of year	7,901	8,563	7,991
Change in fair value of plan assets
Balance at beginning of year	7,877	6,874
Actual return on plan assets	(335)	1,011
Employer contributions	39	345
Benefits paid	(422)	(413)
Foreign exchange rate changes and other	(37)	60
Balance at end of year	7,122	7,877	6,874
Funded status at end of year	(779)	(686)
Postretirement Benefits Other Than Pensions
Change in projected benefit obligation
Projected benefit obligation at beginning of year	289	317
Service cost	3	3	3
Interest cost	10	12	16
Plan participants' contributions	5	5
Actuarial (gains) losses	(22)	(7)
Benefits paid	(35)	(41)
Projected benefit obligation at end of year	250	289	$ 317
Change in fair value of plan assets
Funded status at end of year	$ (250)	(289)
United States \| Pension Benefits
Change in fair value of plan assets
Employer contributions		$ 300

The amount related to defined benefit plan business disposition.

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Amount of gain (loss) from foreign currency exchange rate changes for benefit obligation for plans of a foreign operation whose functional currency is not the reporting currency and other changes not separately disclosed in the financial statements.

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The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency and other changes not separately disclosed in the financial statements.

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Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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