Stock-Based Compensation - Stock-Based Compensation Expense in Future for Outstanding Awards (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
2020	$ 14.9
2021	7.2
2022	0.8
2023	0.3
Total	$ 23.2