Derivatives (Impact of Cash Flow Hedges Table) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Liquids realized loss included in Midstream revenue	$ 380	$ 407	$ 660	$ 395

The amount of net gains or losses on price risk cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income.

No definition available.

Name:	us-gaap_PriceRiskCashFlowHedgeGainOrLossReclassifiedToEarningsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration