Stock-Based Compensation - Stock-Based Compensation Expense in Future for Outstanding Awards (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
2021	$ 15.8
2022	7.0
2023	1.7
2024	1.3
2025	0.5
Total	$ 26.3