Acquisitions and Dispositions Acquisitions and Dispositions (Details) - USD ($) $ in Millions	Aug. 31, 2016	Apr. 25, 2016	Apr. 15, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Proceeds from Texegy Deal			$ 46.9
South Bearhead Creek and Burr Ferry Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Participation Interest Sold in Oil and Gas Properties			75.00%
Net Proceeds from Texegy Deal			$ 46.9
Buyer's Assumption of ARO			$ 6.5
Masters Creek Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Proceeds from Texegy Deal		$ 0.1
Buyer's Assumption of ARO		$ 8.1
Sun TSH Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Proceeds from Texegy Deal	$ 0.9
Buyer's Assumption of ARO	$ 1.8