Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 530.5	$ 463.2	$ 1,662.0	$ 1,431.2
Other operating revenues	10.4	10.3	31.5	30.3
Total operating revenues	540.9	473.5	1,693.5	1,461.5
Operating Segments
Disaggregation of Revenue [Line Items]
Total operating revenues	553.0	486.1	1,731.5	1,498.8
Operating Segments \| Natural Gas Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	365.4	327.9	1,152.7	1,033.2
Other operating revenues	5.4	5.3	17.1	16.0
Total operating revenues	370.8	333.2	1,169.8	1,049.2
Operating Segments \| Natural Gas Liquids Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	172.9	143.2	534.0	421.2
Other operating revenues	9.3	9.7	27.7	28.4
Total operating revenues	182.2	152.9	561.7	449.6
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(7.8)	(7.9)	(24.7)	(23.2)
Other operating revenues	(4.3)	(4.7)	(13.3)	(14.1)
Total operating revenues	(12.1)	(12.6)	(38.0)	(37.3)
Firm Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	489.3	413.3	1,516.3	1,258.3
Firm Service \| Operating Segments \| Natural Gas Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	348.4	312.7	1,097.4	979.3
Firm Service \| Operating Segments \| Natural Gas Liquids Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	148.0	108.5	442.5	302.2
Firm Service \| Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(7.1)	(7.9)	(23.6)	(23.2)
Interruptible Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	15.9	15.0	49.5	47.0
Interruptible Service \| Operating Segments \| Natural Gas Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	16.6	14.9	50.6	46.9
Interruptible Service \| Operating Segments \| Natural Gas Liquids Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0.0	0.1	0.0	0.1
Interruptible Service \| Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(0.7)	0.0	(1.1)	0.0
Other revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	25.3	34.9	96.2	125.9
Other revenues \| Operating Segments \| Natural Gas Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0.4	0.3	4.7	7.0
Other revenues \| Operating Segments \| Natural Gas Liquids Reportable Segment
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	24.9	34.6	91.5	118.9
Other revenues \| Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 0.0	$ 0.0	$ 0.0	$ 0.0