Retirement Plans and Postretirement Costs - Minimal Effect of Health Care Trend on our Postretirement Benefit (Details) $ in Thousands	12 Months Ended
Jun. 28, 2020 USD ($)
Significant Effect of Health Care Trend on the Postretirement Benefit
Effect on postretirement benefit obligation as of July 1, 2018, 1% Increase	$ 3
Effect on postretirement benefit obligation as of July 1, 2018, 1% Decrease	$ (3)

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (m)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration