Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of commodity derivatives

	2012	2013	2014	2015
Oil sales, Bbl/D:	21,000	16,800	7,500	3,000
Natural gas purchases, MMBtu/D:	—	10,000	—	—

Schedule of crude oil three way collars entered

Crude Oil Sales (NYMEX WTI) Three-Way Collars
Term	Average Barrels Per Day	Sold Put / Purchased Put / Sold Call
Full year 2013	800	$75.00 / $95.00 / $101.70
Full year 2013 and 2014	1,000	$70.00 / $90.00 / $100.00
Full year 2014	1,000	$70.00 / $90.00 / $120.00
Full year 2014	1,000	$70.00 / $90.00 / $121.80
Full year 2014	1,500	$70.00 / $90.00 / $100.00
Full year 2014 and 2015	1,000	$70.00 / $90.00 / $104.85
Full year 2015	2,000	$70.00 / $90.00 / $100.00

Schedule of natural gas purchases three-way collars entered

Natural Gas Purchases (NYMEX SoCal Border) Three-Way Collars
Term	Average MMBtus Per Day	Sold Put / Purchased Call / Sold Call
Full year 2013	1,000	$2.90 / $4.00 / $5.00
Full year 2013	1,000	$2.96 / $4.25 / $5.25
Full year 2013	1,000	$2.70 / $4.00 / $5.00
Full year 2013	2,000	$3.03 / $4.25 / $5.25

Schedule of natural gas purchases purchased calls

Natural Gas Purchases (NYMEX SoCal Border) Purchased Calls
Term	Average MMBtus Per Day	Strike Price	Deferred Premium per MMBtu
Full year 2013	1,000	$3.50	$0.43
Full year 2013	1,000	$3.50	$0.46
Full year 2013	1,000	$3.50	$0.4975
Full year 2013	2,000	$3.50	$0.5325

Schedule of derivative assets and liabilities

	September 30, 2012
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	10.6	Derivative liabilities	$	1.3
Long term:
Commodity	Derivative assets	11.1		Derivative liabilities	1.4
Total derivatives		$	21.7		$	2.7

	December 31, 2011
	Derivative Assets			Derivative Liabilities
(in millions)	Balance Sheet Classification	Fair Value		Balance Sheet Classification	Fair Value
Current:
Commodity	Derivative assets	$	6.1	Derivative liabilities	$	20.4
Long term:
Commodity	Derivative assets	7.0		Derivative liabilities	15.5
Total derivatives		$	13.1		$	35.9

Summary of (gains) losses before income taxes of derivative instruments recognized in the condensed statements of income (loss)

		Three Months Ended						Nine Months Ended
(in millions)	Location of Loss (Gain) Recognized in Earnings	September 30,						September 30,
Description of Loss (Gain)		2012			2011			2012			2011
Commodity
Loss reclassified from AOCL into earnings (amortization of frozen amounts)	Oil and natural gas sales	$	2.7		$	15.5		$	7.9		$	45.0
Loss (gain) recognized in earnings (cash settlements and mark-to-market movements)	Realized and unrealized loss (gain) on derivatives, net	28.3			(162.1		)	(56.3		)	(126.4		)
Interest rate
(Gain) loss reclassified from AOCL into earnings (amortization of frozen amounts)	Interest	$	(0.3	)	$	—		$	(1.8	)	$	1.2