Summary of Significant Accounting Policies - Net (loss) earnings per common share (Details) - USD ($)		3 Months Ended	9 Months Ended
Oct. 28, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net earnings (loss)		$ 13,190,000	$ (414,000)	$ 9,361,000	$ 2,597,000
Allocation to nonvested restricted stock awards		(199,000)		(146,000)	(42,000)
Net earnings (loss) available to common stockholders		$ 12,991,000	$ (414,000)	$ 9,215,000	$ 2,555,000
Weighted-average shares outstanding - basic and diluted		35,836,000	35,952,000	35,836,000	35,998,000
Net earnings (loss) per common share - basic and diluted		$ 0.36	$ (0.01)	$ 0.26	$ 0.07
Options outstanding (in shares)		0	0	0	0
Dividends paid				$ 0	$ 0
Annual cash dividend on both classes of common stock
Annual cash dividend declared	$ 0.07

Aggregate dividends declared during the period for each share of common stock outstanding.

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