Commitments and Contingencies Commitments and Contigencies (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($) MMcf MBbls	Sep. 30, 2017 USD ($) MMcf MBbls
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	308,131	308,131
Dollar Commitment ($ in thousands) | $	$ 261,851	$ 261,851
Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	34,714	34,714
Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	15,975	15,975
Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	209,922	209,922
Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	47,520	47,520
First Year Commitment [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	24,455	24,455
Dollar Commitment ($ in thousands) | $	$ 18,410	$ 18,410
First Year Commitment [Member] | Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	7,117	7,117
First Year Commitment [Member] | Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	2,738	2,738
First Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	0	0
First Year Commitment [Member] | Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	14,600	14,600
Second Year Commitment [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	41,215	41,215
Dollar Commitment ($ in thousands) | $	$ 35,170	$ 35,170
Second Year Commitment [Member] | Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	7,117	7,117
Second Year Commitment [Member] | Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	2,738	2,738
Second Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	16,760	16,760
Second Year Commitment [Member] | Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	14,600	14,600
Third Year Commitment [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	55,371	55,371
Dollar Commitment ($ in thousands) | $	$ 44,949	$ 44,949
Third Year Commitment [Member] | Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	7,136	7,136
Third Year Commitment [Member] | Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	2,745	2,745
Third Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	30,850	30,850
Third Year Commitment [Member] | Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	14,640	14,640
Fourth Year Commitment [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	44,560	44,560
Dollar Commitment ($ in thousands) | $	$ 33,776	$ 33,776
Fourth Year Commitment [Member] | Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	7,117	7,117
Fourth Year Commitment [Member] | Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	2,738	2,738
Fourth Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	31,025	31,025
Fourth Year Commitment [Member] | Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	3,680	3,680
commitments 5 years and beyond [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	142,530	142,530
Dollar Commitment ($ in thousands) | $	$ 129,546	$ 129,546
commitments 5 years and beyond [Member] | Appalachiain Basin
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	6,227	6,227
commitments 5 years and beyond [Member] | Utica Shale
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	5,016	5,016
commitments 5 years and beyond [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	131,287	131,287
commitments 5 years and beyond [Member] | Delaware Basin [Member]
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf)	0	0
Supply Contract Expiration Date [Member] | Appalachiain Basin
Supply Commitment
Supply Commitments Contract Expiration Date	Aug. 31, 2022
Supply Contract Expiration Date [Member] | Utica Shale
Supply Commitment
Supply Commitments Contract Expiration Date	Jul. 22, 2023
Supply Contract Expiration Date [Member] | Wattenberg Field
Supply Commitment
Supply Commitments Contract Expiration Date	Mar. 31, 2026
Supply Contract Expiration Date [Member] | Delaware Basin [Member]
Supply Commitment
Supply Commitments Contract Expiration Date	Dec. 31, 2020
Crude Oil [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	6,638	6,638
Crude Oil [Member] | First Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	2,413	2,413
Crude Oil [Member] | Second Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	2,413	2,413
Crude Oil [Member] | Third Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	1,812	1,812
Crude Oil [Member] | Fourth Year Commitment [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	0	0
Crude Oil [Member] | commitments 5 years and beyond [Member] | Wattenberg Field
Supply Commitment
Oil and Gas Delivery Commitments Volumes (MMcf) | MBbls	0	0
Crude Oil [Member] | Supply Contract Expiration Date [Member] | Wattenberg Field
Supply Commitment
Supply Commitments Contract Expiration Date	Jun. 30, 2020
First facilities agreement with midstream provider [Member]
Supply Commitment
incremental volume commitment		51.5
Second facilities agreement with midstream provider [Member]
Supply Commitment
incremental volume commitment		33.5