Note 8 - Share-based Compensation - Restricted Stock Activity (Details) - $ / shares						6 Months Ended
	May 03, 2021	Feb. 08, 2021	Mar. 25, 2020	Apr. 01, 2019	Feb. 25, 2019	Jun. 30, 2021
Restricted Stock [Member]
Outstanding as of beginning of year (in shares)						930,854
Outstanding at beginning of year, grant date fair value (in dollars per share)						$ 19.31
Granted (in shares)						122,166
Granted, grant date fair value (in dollars per share)						$ 37.98
Vested (in shares)						(133,527)
Vested, grant date fair value (in dollars per share)						$ 12.28
Forfeited (in shares)						(31,199)
Forfeited, grant date fair value (in dollars per share)						$ 20.44
Outstanding at end of year (in shares)						888,294
Outstanding at end of year, grant date fair value (in dollars per share)						$ 22.90
Market-based Restricted Stock [Member]
Outstanding as of beginning of year (in shares)						224,774
Outstanding at beginning of year, grant date fair value (in dollars per share)						$ 19.20
Granted (in shares)	6,415	30,616	109,140	29,604	94,247	152,665
Granted, grant date fair value (in dollars per share)						$ 30.85
Vested (in shares)		(231,268)				(231,268)
Vested, grant date fair value (in dollars per share)						$ 26.98
Outstanding at end of year (in shares)						146,171
Outstanding at end of year, grant date fair value (in dollars per share)						$ 20.78