Income Taxes, Components of Deferred Tax Assets and Liabilities Included in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets [Abstract]
Compensation	$ 1,680	$ 1,464
Allowance for credit losses	574	605
Lease obligations - including closed clinics	28,592	28,525
Deferred tax assets	30,846	30,594
Deferred tax liabilities [Abstract]
Depreciation and amortization	(27,290)	(23,836)
Operating lease right-of-use assets	(26,427)	(26,318)
Gain on cash flow hedge	(955)	(1,373)
Change in revaluation of put-right liability	(586)	0
Other	(403)	(370)
Deferred tax liabilities	(55,661)	(51,897)
Net deferred tax liabilities	$ (24,815)	$ (21,303)