Related Party Transactions - Summary of Activity Related to Agreements with Related Party (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Related Party Transaction [Line Items]
Earnings from equity investments	$ 1.0	$ 2.9	$ 1.4	$ 5.6
Distributions received from equity investments			6.1	11.5
LM4
Related Party Transaction [Line Items]
Processing fee incurred	4.7	7.1	9.2	14.0
Earnings from equity investments	1.0	2.9	1.4	5.6
Distributions received from equity investments	$ 1.4	$ 4.0	$ 6.1	$ 11.5

Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

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