Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2012

Retirement Benefits

Schedule of net periodic benefit pension cost

	Three months ended March 31,
	Pension						SERP						OPEB
	2012			2011			2012			2011			2012			2011
Service cost	$	1,628		$	1,393		$	7		$	20		$	565		$	626
Interest cost	2,551			2,591			56			41			1,032			1,130
Expected return on plan assets	(3,076		)	(2,680		)	—			—			(1,041		)	(1,050		)
Amortization of prior service cost (1)	133			133			(2		)	(2		)	(253		)	(253		)
Amortization of net actuarial loss (1)	1,950			1,353			76			33			468			500
Net periodic benefit cost	$	3,186		$	2,790		$	137		$	92		$	771		$	953

	Twelve months ended March 31,
	Pension						SERP						OPEB
	2012			2011			2012			2011			2012			2011
Service cost	$	5,830		$	5,007		$	81		$	73		$	2,205		$	2,254
Interest cost	10,366			10,156			198			155			4,286			4,396
Expected return on plan assets	(11,534		)	(10,044		)	—			—			(4,148		)	(3,927		)
Amortization of prior service cost (1)	532			531			(8		)	(8		)	(1,011		)	(1,011		)
Amortization of net actuarial loss (1)	6,091			4,315			213			98			1,729			1,655
Net periodic benefit cost	$	11,285		$	9,965		$	484		$	318		$	3,061		$	3,367

(1) Amounts are amortized from our regulatory asset originally recorded upon recognizing our net pension liability on the balance sheet.