Acquisitions (Tables)

3 Months Ended

Mar. 31, 2012

Acquisitions [Abstract]

Allocation of the recorded value of net assets acquired in the transaction

	(in millions)
Proved oil and gas properties	$	208.7
Unevaluated oil and gas properties		17.3
Asset retirement obligations		(58.4	)
Total fair value of net assets	$	167.6

Pro forma combined statement of operations data

	Three Months Ended March 31, 2011 (unaudited)
	(in millions, except per share amounts)
Revenues	$	241.1
Income from operations		91.4
Net income		55.9
Basic earnings per share	$	1.14
Diluted earnings per share	$	1.14