Basis of Presentation - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 223.5	$ 288.8
Restricted cash - current	$ 67.5	$ 62.6
Restricted Cash, Current, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets	Prepaid expenses and other current assets
Restricted cash - noncurrent		$ 6.2
Restricted Cash, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other noncurrent assets	Other noncurrent assets
Total cash, cash equivalents and restricted cash	$ 291.0	$ 357.6