Acquisitions And Divestitures (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
Apr. 30, 2013	May 31, 2012 MMcf	Dec. 31, 2011
Acquisitions And Divestitures [Abstract]
Cost to acquire natural gas properties through definitive purchase agreement	$ 93.0
Proceeds from sale of oil and gas property and equipment		$ 164.0
Divested assets, Production in MMcfe per day		24.0
Divested assets, Proved net reserves in Bcfe			143

The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleOfOilAndGasPropertyAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration