Fair Value Measurements - Breakdown by Fair Value Hierarchy Category for Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	$ 17.8	$ 46.2
Liabilities from commodity derivative contracts	362.7	67.6
Carrying Value [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	83.3	134.8
Liabilities from commodity derivative contracts	432.5	186.0
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Cash and cash equivalents	209.0	242.8
Carrying Value [Member] \| TRC Revolver [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	555.0
Carrying Value [Member] \| TRP Revolver [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	170.0	280.0
Carrying Value [Member] \| Partnership's Securitization Facility [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	360.0	350.0
Carrying Value [Member] \| Senior Unsecured Notes [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	6,465.7	6,585.4
Fair Value [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	83.3	134.8
Liabilities from commodity derivative contracts	432.5	186.0
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Cash and cash equivalents	209.0	242.8
Fair Value [Member] \| Level 1 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	0.0	0.0
Liabilities from commodity derivative contracts	0.0	0.0
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Cash and cash equivalents	0.0	0.0
Fair Value [Member] \| Level 2 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	83.3	134.8
Liabilities from commodity derivative contracts	431.0	185.8
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Cash and cash equivalents	0.0	0.0
Fair Value [Member] \| Level 3 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Fair Value:
Assets from commodity derivative contracts	0.0	0.0
Liabilities from commodity derivative contracts	1.5	0.2
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Cash and cash equivalents	0.0	0.0
Fair Value [Member] \| TRC Revolver [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	555.0
Fair Value [Member] \| TRC Revolver [Member] \| Level 1 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| TRC Revolver [Member] \| Level 2 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	555.0
Fair Value [Member] \| TRC Revolver [Member] \| Level 3 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| TRP Revolver [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	170.0	280.0
Fair Value [Member] \| TRP Revolver [Member] \| Level 1 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| TRP Revolver [Member] \| Level 2 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	170.0	280.0
Fair Value [Member] \| TRP Revolver [Member] \| Level 3 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| Partnership's Securitization Facility [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	360.0	350.0
Fair Value [Member] \| Partnership's Securitization Facility [Member] \| Level 1 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| Partnership's Securitization Facility [Member] \| Level 2 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	360.0	350.0
Fair Value [Member] \| Partnership's Securitization Facility [Member] \| Level 3 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| Senior Unsecured Notes [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	6,933.3	7,036.8
Fair Value [Member] \| Senior Unsecured Notes [Member] \| Level 1 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	0.0	0.0
Fair Value [Member] \| Senior Unsecured Notes [Member] \| Level 2 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	6,933.3	7,036.8
Fair Value [Member] \| Senior Unsecured Notes [Member] \| Level 3 [Member]
Financial Instruments Recorded on Our Consolidated Balance Sheets at Carrying Value:
Long-term debt	$ 0.0	$ 0.0

Financial instruments recorded on our consolidated balance sheets at carrying value.

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Financial instruments recorded on our consolidated balance sheets at fair value.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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