Investments - Additional Information (Detail)	Mar. 31, 2018 USD ($) AFS_security	Dec. 30, 2017 USD ($)
Investments, Debt Securities [Abstract]
Number of debt securities issues contributing to total unrealized loss \| AFS_security	474
Total, unrealized Losses \| $	$ 73,117,000	$ 41,863,000

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position.

No definition available.

Name:	ck0000081061_DebtSecuritiesAvailableforsaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	ck0000081061_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant