Related Party Transactions - Summary of Revenues From Contracts With Customers on Disaggregated Basis (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer including assessed tax	$ 313.0	$ 294.8	$ 625.1	$ 583.6
Other income	0.4		0.7
Total revenues	313.4	294.8	625.8	583.6
Oil and Gas Gathering Services
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer including assessed tax	148.4	133.4	293.7	262.1
Processing and Storage Services
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer including assessed tax	116.5	105.3	230.3	208.8
Terminaling and Export Services
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer including assessed tax	30.3	34.9	65.0	67.5
Water Gathering and Disposal Services
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer including assessed tax	$ 17.8	$ 21.2	$ 36.1	$ 45.2