Retirement Benefits (Tables)

9 Months Ended

Sep. 30, 2011

Retirement Benefits

Components of net periodic benefit cost

	Three months ended September 30,
	Pension Benefits						SERP						OPEB
	2011			2010			2011			2010			2011			2010
Service cost	$	1,399		$	1,119		$	23		$	18		$	566		$	585
Interest cost	2,601			2,486			46			37			1,096			1,122
Expected return on plan assets	(2,785		)	(2,419		)	—			—			(1,039		)	(950		)
Amortization of prior service cost (1)	133			133			(2		)	(2		)	(253		)	(253		)
Amortization of net actuarial loss (1)	1,374			930			43			8			441			436
Net periodic benefit cost	$	2,722		$	2,249		$	110		$	61		$	811		$	940

	Nine months ended September 30,
	Pension Benefits						SERP						OPEB
	2011			2010			2011			2010			2011			2010
Service cost	$	4,197		$	3,665		$	70		$	52		$	1,699		$	1,603
Interest cost	7,804			7,586			137			115			3,287			3,247
Expected return on plan assets	(8,354		)	(7,385		)	—			—			(3,118		)	(2,883		)
Amortization of prior service cost (1)	398			399			(6		)	(6		)	(758		)	(758		)
Amortization of net actuarial loss (1)	4,121			2,997			128			72			1,322			1,124
Net periodic benefit cost	$	8,166		$	7,262		$	329		$	233		$	2,432		$	2,333

	Twelve months ended September 30,
	Pension Benefits						SERP						OPEB
	2011			2010			2011			2010			2011			2010
Service cost	$	5,418		$	4,818		$	87		$	68		$	2,234		$	2,060
Interest cost	10,333			10,055			176			152			4,370			4,224
Expected return on plan assets	(10,816		)	(9,980		)	—			—			(4,079		)	(3,843		)
Amortization of prior service cost (1)	532			550			(8		)	(8		)	(1,011		)	(1,011		)
Amortization of net actuarial loss (1)	5,120			3,792			152			98			1,696			1,341
Net periodic benefit cost	$	10,587		$	9,235		$	407		$	310		$	3,210		$	2,771

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