Acquisitions (Tables)

6 Months Ended

Jun. 30, 2012

Acquisitions [Abstract]

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

	(in millions)
Proved oil and gas properties	$	39.2
Unevaluated oil and gas properties		1.6
Asset retirement obligations		(14.4	)
Total fair value of net assets	$	26.4

Pro forma combined statement of operations data

	Three Months Ended June  30, 2011 (unaudited)		Six Months Ended June 30, 2011 (unaudited)
	(in millions, except per share amounts)
Revenues	$	279.4	$	515.0
Income from operations		117.2		204.9
Net income		72.1		125.5
Basic earnings per share	$	1.47	$	2.56
Diluted earnings per share	$	1.47	$	2.56