Acquisitions (Tables)

3 Months Ended

Mar. 31, 2013

Acquisitions [Abstract]

Schedule of Purchase Price Allocation [Table Text Block]

The following table presents a summary of the Company's preliminary purchase accounting entries:

	As of March 31, 2013
	(in millions)
Consideration given:
Cash consideration	$	1,394.2
Amounts recognized for preliminary fair value of assets acquired and liabilities assumed:
Proved properties	$	713.8
Unproved properties	684.9
Asset retirement obligations	(0.9		)
Liabilities assumed	(4.4		)
Other assets	0.8
Total fair value	$	1,394.2

Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]

Business Acquisition, Pro Forma Information [Table Text Block]

The following unaudited, pro forma results of operations are provided for the three months ended March 31, 2012. These supplemental pro forma results of operations are provided for illustrative purposes only and may not be indicative of the actual results that would have been achieved by the properties for the period presented or that may be achieved by the properties in the future. Future results may vary significantly from the results reflected in this pro forma financial information because of future events and transactions, as well as other factors. The pro forma information is based on QEP's consolidated results of operations for the three months ended March 31, 2012, on the acquired properties' historical results of operations and on estimates of the effect of the transaction on the combined results. The pro forma results of operations have been prepared by adjusting the historical results of QEP to include the historical results of the acquired properties based on information provided by the seller and the impact of the preliminary purchase price allocation. The pro forma results of operations do not include any cost savings or other synergies that may result from the 2012 Acquisition or any estimated costs that have been or will be incurred by the Company to integrate the properties.

	Three Months Ended
	March 31, 2012
	Actual		Pro forma
	(in millions, except per share data)
Revenues	$	603.2	$	637.9
Net income attributable to QEP	155.2		173.0
Earnings per common share attributable to QEP
Basic	$	0.87	$	0.97
Diluted	0.87		0.97