Special Charges - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Special charges	$ 0	$ 0	$ 40,885,000
Employee Severance
Restructuring Cost and Reserve [Line Items]
Special charges			23,500,000
Contract Termination
Restructuring Cost and Reserve [Line Items]
Special charges			14,400,000
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Special charges			$ 3,000,000.0