Investments in Unconsolidated Affiliates and Variable Interest Entities - Schedule of Unaudited, Condensed Balance Sheet Information for Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	Dec. 27, 2020	Sep. 27, 2020	Jun. 28, 2020	Dec. 29, 2019	Sep. 29, 2019	Jun. 30, 2019
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 297,499		$ 254,493
Current liabilities	80,952		54,994
Shareholders’ equity and capital accounts	334,873	$ 320,077	316,155	$ 395,479	$ 390,007	$ 392,845
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule Of Equity Method Investments [Line Items]
Current assets	7,499		5,190
Non-current assets	731		561
Current liabilities	3,166		1,415
Shareholders’ equity and capital accounts	5,064		4,336
UNIFI’s portion of undistributed earnings	2,041		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	7,499		5,190
Non-current assets	731		561
Current liabilities	3,166		1,415
Shareholders’ equity and capital accounts	5,064		4,336
UNIFI’s portion of undistributed earnings	$ 2,041		$ 1,424