Summary of Significant Accounting Policies Revenue Recognition (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Gas Balancing Asset (Liability)	$ 3.5	$ 7.9

The value of gas balancing asset or liability as of the end of the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=27015464&loc=d3e512571-122862

Name:	us-gaap_GasImbalanceAssetLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant