Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($)	Cumulative Preferred Stock [Member]	Cumulative Convertible Preferred Stock [Member]	Participating Convertible Preferred Stock [Member]	Series 2003 Convertible Preferred Stock [Member]	Common Class A [Member]	Common Class B [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Preferred Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Treasury Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Balance at Mar. 31, 2019													$ 707,000	$ 3,039,000	$ 98,260,000	$ (75,740,000)	$ (18,285,000)	$ 409,504,000
Net earnings (loss)													0	0	0	0	0	1,103,000
Cash dividends declared on preferred stock													0	0	0	0	0	(12,000)
Equity incentive program													0	0	25,000	0	0	0
Purchase treasury stock													0	0	0	(2,744,000)	0	0
Balance (Accounting Standards Update 2016-02 [Member]) at Jun. 29, 2019							$ 0	$ 0	$ 0	$ 0	$ 0	$ (2,019,000)
Balance at Jun. 29, 2019													707,000	3,039,000	98,285,000	(78,484,000)	(18,285,000)	408,576,000
Balance at Mar. 31, 2019													707,000	3,039,000	98,260,000	(75,740,000)	(18,285,000)	409,504,000
Net earnings (loss)																			$ 31,121,000
Balance at Dec. 28, 2019													703,000	3,040,000	98,338,000	(87,194,000)	(18,285,000)	438,583,000	435,185,000
Balance at Jun. 29, 2019													707,000	3,039,000	98,285,000	(78,484,000)	(18,285,000)	408,576,000
Net earnings (loss)													0	0	0	0	0	4,635,000
Equity incentive program													0	0	25,000	0	0	0
Purchase treasury stock													0	0	0	(5,836,000)	0	0
Preferred stock conversion													(4,000)	1,000	3,000	0	0	0
Balance at Sep. 28, 2019													703,000	3,040,000	98,313,000	(84,320,000)	(18,285,000)	413,211,000
Net earnings (loss)													0	0	0	0	0	25,383,000	25,383,000
Cash dividends declared on preferred stock													0	0	0	0	0	(11,000)
Equity incentive program													0	0	25,000	0	0	0
Purchase treasury stock													0	0	0	(2,874,000)	0	0
Balance at Dec. 28, 2019													703,000	3,040,000	98,338,000	(87,194,000)	(18,285,000)	438,583,000	435,185,000
Balance at Mar. 31, 2020													681,000	3,041,000	98,384,000	(88,319,000)	(79,220,000)	459,797,000	394,364,000
Net earnings (loss)													0	0	0	0	0	20,706,000
Cash dividends declared on preferred stock													0	0	0	0	0	(12,000)
Equity incentive program													0	0	28,000	0	0	0
Balance at Jun. 27, 2020													681,000	3,041,000	98,412,000	(88,319,000)	(79,220,000)	480,491,000
Balance at Mar. 31, 2020													681,000	3,041,000	98,384,000	(88,319,000)	(79,220,000)	459,797,000	394,364,000
Net earnings (loss)																			111,271,000
Purchase treasury stock					$ (2,154,000)	$ 0
Balance at Dec. 26, 2020													678,000	3,041,000	98,462,000	(90,473,000)	(79,220,000)	571,045,000	503,533,000
Balance at Jun. 27, 2020													681,000	3,041,000	98,412,000	(88,319,000)	(79,220,000)	480,491,000
Net earnings (loss)													0	0	0	0	0	18,105,000
Equity incentive program													0	0	24,000	0	0	0
Purchase treasury stock													0	0	0	(1,163,000)	0	0
Balance at Sep. 26, 2020													681,000	3,041,000	98,436,000	(89,482,000)	(79,220,000)	498,596,000
Net earnings (loss)													0	0	0	0	0	72,460,000	72,460,000
Cash dividends declared on preferred stock													0	0	0	0	0	(11,000)
Equity incentive program													0	0	23,000	0	0	0
Purchase treasury stock													0	0	0	(991,000)	0	0
Preferred stock conversion													(3,000)	0	3,000	0	0	0
Balance at Dec. 26, 2020													$ 678,000	$ 3,041,000	$ 98,462,000	$ (90,473,000)	$ (79,220,000)	$ 571,045,000	$ 503,533,000
Preferred stock, shares authorized (in shares)	200,000	1,400,000	35,105	500
Common stock, shares authorized (in shares)					20,000,000	10,000,000
Preferred stock, outstanding (in shares)	200,000	807,240	35,105	500
Common stock, shares outstanding (in shares)					7,350,186	1,718,002