Investments in Unconsolidated Affiliates and Variable Interest Entities - Schedule of Unaudited, Condensed Balance Sheet Information for Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	Mar. 28, 2021	Dec. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 29, 2019	Jun. 30, 2019
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 312,659		$ 254,493
Current liabilities	100,610		54,994
Shareholders’ equity and capital accounts	335,597	$ 334,873	316,155	$ 333,829	$ 395,479	$ 392,845
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule Of Equity Method Investments [Line Items]
Current assets	8,473		5,190
Non-current assets	693		561
Current liabilities	3,472		1,415
Shareholders’ equity and capital accounts	5,694		4,336
UNIFI’s portion of undistributed earnings	2,486		1,424
Equity Method Investment, Nonconsolidated Investee or Group of Investees | UNF and UNF America [Member]
Schedule Of Equity Method Investments [Line Items]
Current assets	8,473		5,190
Non-current assets	693		561
Current liabilities	3,472		1,415
Shareholders’ equity and capital accounts	5,694		4,336
UNIFI’s portion of undistributed earnings	$ 2,486		$ 1,424