Regulatory assets and liabilities consist of the following (dollars in millions):



		Weighted Average Remaining Life ⁽¹⁾	As of December 31,
			2011				2010
			Current		Noncurrent		Current		Noncurrent
Regulatory assets:
	Price risk management ⁽²⁾	2 years	$	194	$	172	$	175	$	185
	Pension and other postretirement plans ⁽²⁾	⁽³⁾	—		295		—		213
	Deferred income taxes ⁽²⁾	⁽⁴⁾	—		87		—		95
	Deferred broker settlements ⁽²⁾	1 year	11		—		24		—
	Renewable energy deferral	1 year	1		—		22		—
	Debt reacquisition costs ⁽²⁾	7 years	—		28		—		23
	Other ⁽⁵⁾	Various	10		12		—		28
	Total regulatory assets		$	216	$	594	$	221	$	544
Regulatory liabilities:
	Asset retirement removal costs ⁽⁶⁾	⁽⁴⁾	$	—	$	637	$	—	$	588
	Asset retirement obligations ⁽⁶⁾	⁽⁴⁾	—		36		—		33
	Power cost adjustment mechanism	⁽⁷⁾	—		10		—		—
	Trojan ISFSI pollution control tax credits	⁽⁷⁾	—		7		18		4
	Other	Various	6		30		7		32
	Total regulatory liabilities		$	6	$	720	$	25	$	657


(1)	As of December 31, 2011.


(2)	Does not include a return on investment.


(3)	Recovery expected over the average service life of employees. For additional information, see Note 2, Summary of Significant Accounting Policies.


(4)	Recovery expected over the estimated lives of the assets.


(5)	Of the total other unamortized regulatory asset balances, a return is recorded on $21 million and $26 million as of December 31, 2011 and 2010, respectively.


(6)	Included in rate base for ratemaking purposes.


(7)	Refund period not yet determined.