Retirement Plans - Fair Value of Defined Benefit Plans' Assets by Asset Fair Value Hierarchy Level (Details) - USD ($) $ in Millions	Dec. 29, 2018	Dec. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 836	$ 851
Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	340	529
Total investments measured at net asset value as a practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	496	322
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	8
Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	34
Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1
Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		34
Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	32
Mutual Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		37
Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	236	224
Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	26
Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	155
Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	4
Debt Securities | Government agencies securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		8
Common Collective Trust Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40	63
Common Collective Trust Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	156	249
Common Collective Trust Funds | Treasury STRIPS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	291
Common Collective Trust Funds | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	10
Level 1 | Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61	112
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	8
Level 1 | Equities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	34
Level 1 | Equities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1
Level 1 | Equities | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Level 1 | Equities | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		34
Level 1 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	32
Level 1 | Mutual Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		37
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 1 | Debt Securities | Government agencies securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 2 | Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	279	417
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 | International equities
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 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Mutual Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Level 2 | Debt Securities | Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	236	224
Level 2 | Debt Securities | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	26
Level 2 | Debt Securities | U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	155
Level 2 | Debt Securities | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	4
Level 2 | Debt Securities | Government agencies securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		8
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 | International equities
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 | Mutual Funds | International equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Mutual Funds | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		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
Level 3 | Debt Securities | Government agencies securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 0