Income Taxes - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) Provision	Dec. 31, 2017 USD ($)	Dec. 21, 2017 USD ($)
Income Taxes [Line Items]
Reduction in corporate tax rate		21.00%	21.00%	21.00%	35.00%
Tax code changes description		The TCJA-17 made broad and complex changes to the U.S. tax code, including, but not limited to, (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) requiring a current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations through the implementation of a territorial tax system; (5) creating a new limitation on deductible interest expense; and (6) limiting certain other deductions.
Provisional decrease in deferred tax assets					$ 97,000,000
Provisional decrease in deferred tax liabilities					127,000,000
Net adjustment to deferred tax benefit					30,000,000
Completion of 2017 tax return, increase in deferred tax assets	$ 1,000,000
Completion of 2017 tax return, decrease in deferred tax liabilities	5,000,000
Completion of 2017 tax return, Adjustment to deferred tax benefit	6,000,000
Estimated transition tax obligations					$ 11,300,000
Increase in transition tax				$ 100,000
TCJA 2017, completion of accounting, estimated transition tax obligations				$ 11,400,000
Number of anti-base erosion tax provisions | Provision				2
Provisional deferred tax - GILTI		$ 0	$ 0
Foreign pre-tax earnings		72,000,000	69,000,000	$ 84,000,000
Unremitted foreign earnings						$ 0
Qualified dividend received deduction		110,000,000
Tax expense (benefit) from employee share-based payments		$ 7,000,000	$ (12,000,000)	$ (1,000,000)
Effective tax rates		23.90%	22.40%	22.90%
Deferred federal state and foreign tax benefit		$ 11,000,000	$ 8,000,000
Future taxable income, amount		951,000,000,000
Deferred state tax benefit (net of the federal benefit)		(4,114,000)	(11,106,000)	$ (3,592,000)
Deferred foreign tax benefit		10,000,000
Valuation allowances		68,003,000	75,277,000
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	$ 71,000,000		64,000,000	$ 71,000,000
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		4,000,000	$ 4,000,000
State and Local Jurisdiction
Income Taxes [Line Items]
Deferred state tax benefit (net of the federal benefit)		66,000,000
Interest expense carryforwards		141,000,000
Interest expense, deferred tax benefit		5,000,000
Foreign Tax Authority
Income Taxes [Line Items]
Net operating losses and interest expense		$ 45,000,000