Subsequent Event Subsequent Event (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended
	Oct. 08, 2013	Oct. 08, 2013 Shallow Upper Devonian Sale	Oct. 08, 2013 PDCE proportionate share Shallow Upper Devonian Sale	Sep. 30, 2013 Shallow Upper Devonian Letter of Credit
Subsequent Event:
Purchase and Sale Agreement Execution Date	Oct. 08, 2013
Oil and gas assets sale price before adjustments ($ in millions)		$ 18.8	$ 6.2
PDC Irrevocable Standby Letter of Credit ($)				$ 6.7