Long-Term Debt (Narrative) (Details)		3 Months Ended	12 Months Ended
Long-Term Debt (Narrative) (Details)	Dec. 27, 2016 USD ($)	Mar. 31, 2018 USD ($) financial_ratio	Dec. 31, 2016	Dec. 31, 2017 USD ($)	Aug. 10, 2015 USD ($)	Sep. 26, 2014 USD ($)
Debt Instrument [Line Items]
Letters of credit outstanding, amount		$ 1,900,000
Senior Notes \| 2025 Senior Notes
Debt Instrument [Line Items]
Long term debt		$ 450,000,000		$ 450,000,000
Debt issued, face amount	$ 450,000,000.0
Stated interest rate		5.25%
Senior Notes \| 2025 Senior Notes \| January 15, 2020
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed	103.938%
Senior Notes \| 2025 Senior Notes \| January 1, 2023
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed	100.00%
Senior Notes \| 2025 Senior Notes \| Prior To January 15, 2020
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed			100.00%
Senior Unsecured Notes \| 2025 Senior Notes \| Event of change in control
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed	101.00%
Senior Unsecured Notes \| 6.625% Notes due 2022
Debt Instrument [Line Items]
Long term debt		$ 700,000,000		700,000,000
Debt issued, face amount					$ 200,000,000.0	$ 500,000,000.0
Stated interest rate		6.625%			6.625%
Percentage of principal amount issued					99.25%
Senior Unsecured Notes \| 6.625% Notes due 2022 \| After October 1, 2017
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed		104.969%
Senior Unsecured Notes \| 6.625% Notes due 2022 \| January 1, 2020
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed		100.00%
Senior Unsecured Notes \| 6.625% Notes due 2022 \| Event of change in control
Debt Instrument [Line Items]
Percentage of original principal amount of debt at which debt can be redeemed		101.00%
Revolving credit facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity		$ 1,500,000,000
Line of credit facility, maximum borrowing capacity, elected commitment		900,000,000
Credit agreement, maximum borrowing capacity, lender commitments		$ 2,500,000,000
Number of financial ratios \| financial_ratio		2
Working capital ratio, required		1.0
Leverage ratio, required		4.25
Weighted average interest rate		3.90%
Credit agreement, remaining borrowing capacity		$ 453,100,000
Revolving credit facility \| Line of Credit
Debt Instrument [Line Items]
Long term debt		$ 445,000,000		$ 375,000,000
Revolving credit facility \| Eurodollar
Debt Instrument [Line Items]
Variable rate basis, base percentage prior to adjustments		100.00%
Revolving credit facility \| Eurodollar \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Line of credit facility, unused capacity, commitment fee percentage		0.375%
Revolving credit facility \| Eurodollar \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.50%
Line of credit facility, unused capacity, commitment fee percentage		0.50%
Revolving credit facility \| Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Revolving credit facility \| Adjusted LIBOR rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Revolving credit facility \| Adjusted LIBOR rate \| Minimum
Debt Instrument [Line Items]
Interest rate terms, percentage of borrowing base utilized margin		0.50%
Revolving credit facility \| Adjusted LIBOR rate \| Maximum
Debt Instrument [Line Items]
Interest rate terms, percentage of borrowing base utilized margin		1.50%

RSP Permian, Inc. 10-Q