Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580

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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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The Effect of Derivative Instruments on the Consolidated Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Jun. 30, 2014
Derivative [Line Items]
Derivative, Cash Received on Hedge	$ (47,103)	$ 84,331
Unrealized Gain (Loss) on Commodity Derivatives	(22,463)	55,060
Accumulated Other Comprehensive Income (Loss), Net of Tax	(389,042)		$ (392,556)
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	0	(9,814)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		(9,814)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	24,640	(29,271)
Gain (Loss) on Hedging Activity	(22,463)	55,060
Swap [Member]
Derivative [Line Items]
Derivative, Cash Received on Hedge	(24,607)	82,146
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	162,604	(38,023)
Gain (Loss) on Hedging Activity	137,997	44,123
Swap [Member] \| Cash Flow Hedging [Member] \| Natural Gas [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		0		$ 43,470
Propane [Member]
Derivative [Line Items]
Derivative, Cash Received on Hedge	(1,216)	0
Basis Swap [Member]
Derivative [Line Items]
Derivative, Cash Received on Hedge		2,185
Derivative, Cost of Hedge Net of Cash Received	(21,280)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(139,111)	(6,421)
Gain (Loss) on Hedging Activity	(160,391)	(4,236)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	0	15,438
Gain (Loss) on Hedging Activity	0	15,438
Natural Gas Liquids [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	1,147	(265)
Gain (Loss) on Hedging Activity	(69)	(265)
Revenue Mineral Sales [Member] \| Swap [Member] \| Cash Flow Hedging [Member] \| Natural Gas [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 0	$ 33,656