Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Measurements

Derivative instrument assets and liabilities measured at fair value on a recurring basis

			Fair value measurements at reporting date using
Description	March 31, 2013		Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(Thousands)
Assets
Derivative instruments, at fair value	$	183,727	$	1,588	$	105,620	$	76,519
Liabilities
Derivative instruments, at fair value	$	92,107	$	2,382	$	83,071	$	6,654

			Fair value measurements at reporting date using
Description	December 31, 2012		Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(Thousands)
Assets
Derivative instruments, at fair value	$	304,237	$	1,228	$	204,592	$	98,417
Liabilities
Derivative instruments, at fair value	$	75,562	$	1,609	$	66,250	$	7,703

Fair value measurements using significant unobservable inputs (Level 3)

Fair value measurements using significant unobservable inputs (Level 3)
		Derivative instruments, at fair value, net Three Months Ended March 31,
		2013			2012
		(Thousands)
Balance at January 1	$	90,714		$	143,260
Total gains or losses:
Included in earnings		423			–
Included in OCI		(11,733	)		31,596
Purchases		72			–
Settlements		(9,611	)		(18,790	)
Transfers in and/or out of Level 3		–			–
Balance at March 31	$	69,865		$	156,066