Long-Term Debt and Short-Term Borrowings - Schedule of debt (Details) - USD ($)		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 30, 2021	Oct. 01, 2021	Sep. 30, 2021
Debt Disclosure [Abstract]
Principal and interest payments	$ 39,000	$ 39,000	$ 39,000
Interest rate of unsecured term note	5.75%	5.75%
Mortgage notes	$ 24,482,000	$ 24,482,000	24,388,000
Senior notes	100,000,000	100,000,000	90,000,000
Unsecured term note due February 2025, with monthly principal and interest payments of $39, bearing interest at 5.75%	1,735,000	1,735,000	1,356,000
Convertible senior notes	100,050,000	100,050,000	100,050,000
Payroll Protection Program loans	3,424,000	3,424,000	3,181,000
Revolving credit agreement	0	0	0
Debt issuance costs	(3,684,000)	(3,684,000)	(3,831,000)
Long-term debt	226,007,000	226,007,000	215,144,000
Less current maturities, net of issuance costs	10,548,000	10,548,000	10,967,000
Less debt discount	22,423,000	22,423,000	0
Long-term debt	193,036,000	193,036,000	204,177,000
Short-term borrowings	87,194,000	87,194,000	47,346,000	$ 50,000,000	$ 83,500,000
Total debt and short-term borrowings, net of issuance costs	$ 313,201,000	$ 313,201,000	$ 262,490,000