Income Taxes - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 Provision
Income Taxes [Line Items]
Number of anti-base erosion tax provisions | Provision				2
Provisional deferred tax - GILTI	$ 0	$ 0	$ 0
Foreign pre-tax earnings	79,000,000	72,000,000	69,000,000
Qualified dividend received deduction	116,000,000
Tax expense (benefit) from employee share-based payments	$ (2,000,000)	$ 7,000,000	$ (12,000,000)
Effective tax rates	23.60%	23.90%	22.40%
Deferred federal state and foreign tax benefit	$ 6,000,000	$ 11,000,000
Future taxable income, amount	891,000,000
Deferred state tax benefit (net of the federal benefit)	(4,420,000)	(4,114,000)	$ (11,106,000)
Deferred foreign tax benefit	13,000,000
Deferred federal tax benefits	26,638,000	20,382,000	27,073,000
State tax benefits	(44,993,000)	(43,333,000)	$ (40,152,000)
Valuation allowances	62,356,000	68,003,000
Increase in estimated liabilities for uncertain tax positions	1,000,000	1,000,000
Impact of unrecognized tax benefits if recognized	$ 2,000,000	2,000,000
Period of expiration of the statute of limitations for certain jurisdictions	within the next twelve months
Jurisdictions statutes of limitations expiration period	12 months
Maximum
Income Taxes [Line Items]
Accrued interest and penalties	$ 1,000,000	1,000,000
Foreign and U.S. state and local jurisdictions have statutes of limitations, in years	4 years
Minimum
Income Taxes [Line Items]
Foreign and U.S. state and local jurisdictions have statutes of limitations, in years	3 years
Allowance in relation to state tax benefit
Income Taxes [Line Items]
Valuation allowances	$ 57,000,000	64,000,000
Net Operating Losses Not Realized
Income Taxes [Line Items]
Decrease in valuation allowance	7,000,000
Foreign Net Operating Losses and Credit Carryforwards
Income Taxes [Line Items]
Decrease in valuation allowance	5,000,000	$ 4,000,000
State and Local Jurisdiction
Income Taxes [Line Items]
Deferred state tax benefit (net of the federal benefit)	60,000,000
Interest expense carryforwards	158,000,000
Interest expense, deferred tax benefit	5,000,000
Foreign Tax Authority
Income Taxes [Line Items]
Net operating losses and interest expense	51,000,000
Riverside Medical Clinic Patient Services, LLC
Income Taxes [Line Items]
Operating loss carry forward federal and state	11,000,000
Operating loss carry forward state	10,000,000
Deferred federal tax benefits	2,000,000
State tax benefits	$ 1,000,000