Fair Value Measurements

12 Months Ended

Dec. 31, 2011

Fair Value Measurements [Abstract]

FAIR VALUE MEASUREMENTS

4. FAIR VALUE MEASUREMENTS.

We are entitled to collect in rates the amounts necessary to fund our ARO. We deposit monthly, into an external trust account, the revenues specifically designated for ARO. We established the ARO trust account (ARO Trust) on June 30, 2008. The ARO Trust carries a moderate risk portfolio. We measure the financial instruments held in our ARO Trust at fair value. However, in accordance with the ASC Topic 980, Regulated Operations, both realized and unrealized gains and losses of the ARO Trust are recorded as regulatory assets or liabilities.

       The fair value hierarchy prioritizes the inputs used to measure fair value, giving the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). We classify our ARO Trust within Level 1 of the hierarchy. Our ARO Trust consists of the following financial instruments (in millions):

		December 31,
		2011		2010
Money market funds		$	1.4	$	1.6
U.S. equity funds			9.5		17.4
International equity funds			5.3		6.0
Municipal bond funds			8.3		15.4
	Total	$	24.5	$	40.4

Reclassifications of fair value between Level 1, Level 2, and Level 3 of the fair value hierarchy, if applicable, are made at the end of each quarter. No such transfers occurred during the period ended December 31, 2011.