Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Benefit And Retirement Plans [Line Items]
Defined contribution plan, employer contribution	$ 10	$ 10	$ 11
Postretirement Defined Benefit Plans, Liabilities	$ 7	$ 7
Maximum
Employee Benefit And Retirement Plans [Line Items]
Defined contribution plan, employer matching percentage	6.00%
If employees are under age 40 [Member]
Employee Benefit And Retirement Plans [Line Items]
Defined contribution plan, employer matching percentage	6.00%
If employees are 40 years or older [Member]
Employee Benefit And Retirement Plans [Line Items]
Defined contribution plan, employer matching percentage	8.00%