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Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 29, 2025	Dec. 31, 2025	Jun. 25, 2025	Jun. 24, 2025	Dec. 28, 2024
Goodwill And Intangible Assets Disclosure [Line Items]
Goodwill	$ 200,000		$ 200,135	$ 199,053	$ 199,053	$ 239,583
Finite-lived intangible assets, aggregate amortization expense	25,267	$ 5,950
Behavioral Reporting Unit
Goodwill And Intangible Assets Disclosure [Line Items]
Goodwill	$ 161,790
Percentage of goodwill held	80.90%	62.70%
Behavioral Reporting Unit \| Maximum
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value in excess of carrying amount	5.00%
Behavioral Reporting Unit \| Minimum
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value in excess of carrying amount		55.00%
Clinical Reporting Unit
Goodwill And Intangible Assets Disclosure [Line Items]
Goodwill	$ 38,210
Percentage of goodwill held	19.10%	37.30%
Clinical Reporting Unit \| Minimum
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value in excess of carrying amount		60.00%
Trade Name \| Maximum
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value of asset in excess of carrying amount	10.00%
Franchise rights acquired \| United States
Goodwill And Intangible Assets Disclosure [Line Items]
Indefinite-lived intangible assets, impairment charges		$ 27,549
Indefinite-lived franchise rights acquired percentage		100.00%
Impairment, Intangible Asset, Indefinite-Lived (Excluding Goodwill), Statement of Income or Comprehensive Income [Extensible Enumeration]		Asset Impairment Charges