Basis of Presentation - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 237.2	$ 288.8
Restricted cash - current	$ 58.9	$ 62.6
Restricted Cash, Current, Asset, Statement of Financial Position [Extensible List]	Prepaid expenses and other current assets	Prepaid expenses and other current assets
Restricted cash - noncurrent	$ 0.1	$ 6.2
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	Other noncurrent assets	Other noncurrent assets
Total cash, cash equivalents and restricted cash	$ 296.2	$ 357.6