Restructuring Charges - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Dec. 31, 2018	Sep. 30, 2019
Restructuring And Related Activities [Abstract]
Lease term expiration		lease terms expiring between 2023 and 2026
Lease exit and severance charges	$ 7.3	$ 5.9