Commitments and Contingencies - Additional Information (Detail) £ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2022 GBP (£)	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2022 GBP (£)	Dec. 31, 2020 USD ($)	Jun. 01, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability, current		$ 74,000,000			$ 74,000,000						$ 74,000,000
Compensation liability claims		115,000,000			115,000,000						118,000,000
Compensation and related benefits		55,000,000			55,000,000						$ 55,000,000
Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Repayment of legal settlement amount on demand						$ 4,000,000	$ 4,000,000	$ 4,000,000	$ 4,000,000	$ 4,000,000
Amount claimed from over payments of legal settlements						7,000,000	8,000,000	7,000,000	$ 4,000,000
Amount claimed from over payments of legal settlements due to change in calculations						3,000,000	2,000,000	$ 2,000,000
Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Maximum insurance deductible														$ 2,500,000
Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Property insurance | £	£ 1,500
Maximum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses														$ 1,000,000,000
Percentage of insurance deductible											5.00%	5.00%
Maximum | Earthquake | LAS VEGAS, NEVADA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											$ 200,000,000
Maximum | Earthquake | CALIFORNIA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											150,000,000
Maximum | Earthquake | Faulty Zones of UNITED STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											100,000,000
Maximum | Earthquake | PUERTO RICO
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											40,000,000
Maximum | Earthquake | OTHER STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											250,000,000
Maximum | Flood
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											100,000,000
Maximum | Flood | PUERTO RICO
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											1,000,000
Maximum | Flood | Texas
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses											$ 10,000,000
Minimum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Percentage of insurance deductible											3.00%	3.00%
General And Professional Liability Insurance Policies
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability		36,000,000	$ 5,000,000	$ 11,000,000	52,000,000
General and Professional Liability
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability		349,000,000			349,000,000						$ 358,000,000
Subsidiaries | Professional Liability
Commitments and Contingencies Disclosure [Line Items]
Purchased several excess policies through commercial insurance carriers per occurrence															$ 2,500,000
Purchased several excess policies through commercial insurance carriers per occurrence excess claim amount															10,000,000
Subsidiaries | Professional Liability | Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability | £												£ 16
Subsidiaries | Professional Liability | Maximum
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability		20,000,000			20,000,000						20,000,000				10,000,000	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 10,000,000
Subsidiaries | General Liability | Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability | £												£ 25
Subsidiaries | General Liability | Maximum
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability		3,000,000			3,000,000						3,000,000				$ 3,000,000	3,000,000	3,000,000	3,000,000	3,000,000
Subsidiaries | General And Professional Liability Insurance Policies | Maximum
Commitments and Contingencies Disclosure [Line Items]
Purchased several excess policies through commercial insurance carriers per occurrence		$ 155,000,000			$ 155,000,000	$ 250,000,000	$ 250,000,000				$ 162,500,000		$ 250,000,000			$ 250,000,000	$ 250,000,000	$ 250,000,000	$ 250,000,000