Employee Benefit Plans

6 Months Ended

Jun. 30, 2011

Employee Benefit Plans [Abstract]

EMPLOYEE BENEFIT PLANS

NOTE 7. EMPLOYEE BENEFIT PLANS

COMPONENTS OF NET PERIODIC BENEFIT COST

The components of UniSource Energy’s net periodic benefit cost are as follows:

							Other Postretirement
	Pension Benefits						Benefits
	Three Months Ended						Three Months Ended
	June 30,						June 30,
	2011			2010			2011		2010
	-Millions of Dollars-
Components of Net Periodic Benefit Cost
Service Cost	$	2		$	2		$	1	$	—
Interest Cost		4			4			1		1
Expected Return on Plan Assets		(4	)		(3	)		—		—
Amortization of Net Loss		2			1			—		—
Net Periodic Benefit Cost	$	4		$	4		$	2	$	1

The table above includes pension benefit costs of less than $0.5 million and other postretirement benefit costs of less than $0.1 million for UNS Gas and UNS Electric. The remaining cost is related to TEP.

							Other Postretirement
	Pension Benefits						Benefits
	Six Months Ended						Six Months Ended
	June 30,						June 30,
	2011			2010			2011			2010
	-Millions of Dollars-
Components of Net Periodic Benefit Cost
Service Cost	$	5		$	4		$	2		$	1
Interest Cost		8			8			2			2
Expected Return on Plan Assets		(8	)		(7	)		—			—
Amortization of Prior Service Costs		—			—			(1	)		—
Amortization of Net Loss		3			2			—			—
Net Periodic Benefit Cost	$	8		$	7		$	3		$	3

The table above includes pension benefit costs of $1 million and other postretirement benefit costs of less than $0.1 million for UNS Gas and UNS Electric. The remaining cost is related to TEP.