Retirement Plans Fair Value of Defined Benefit Plans' Assets by Asset Fair Value Hierarchy Level (Details) - USD ($) $ in Millions	Dec. 28, 2019	Dec. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 923	$ 836
Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	371	340
Total investments measured at net asset value as a practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	552	496
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	5
Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46
Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2
Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		34
Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	21
Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	248	236
Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38	33
Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	8
Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Common Collective Trust Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	193	156
Common Collective Trust Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	40
Common Collective Trust Funds | Treasury STRIPS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	293	291
Common Collective Trust Funds | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	9
Level 1 | Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	77	61
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	5
Level 1 | Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46
Level 1 | Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2
Level 1 | Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		34
Level 1 | Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Level 1 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	21
Level 1 | Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	294	279
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Level 2 | Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Level 2 | Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 2 | Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 2 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	248	236
Level 2 | Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38	33
Level 2 | Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	8
Level 2 | Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Level 3 | Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Level 3 | Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Level 3 | Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 3 | Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 3 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0