Pension and Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Defined benefit plan contributions	$ 0.1	$ 0.2
Unfunded liability plans	$ 8.7		$ 8.9