Other Investments- Summary Financial Information for DCIP (Detail) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Equity Method Investments [Line Items]
Total revenue	$ 650.4			$ 434.8			$ 1,855.0	$ 843.8
Net income (loss)	(23.9)	$ (72.8)	$ (72.5)	(77.6)	$ (142.2)	$ (208.9)	(169.2)	(428.7)
Current assets	800.9						800.9		$ 874.4
Current liabilities	628.4						628.4		769.1
Noncurrent liabilities	4,016.7						4,016.7		4,127.0
Members' equity	$ 205.4	$ 218.7	$ 299.4	$ 314.8	$ 397.7	$ 523.8	$ 205.4	$ 314.8	$ 334.5	$ 798.9