Benefit Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2012

Benefit Plans and Other Postretirement Benefits

Schedule of components of net pension expense

	Pension Benefits						Other Postretirement Benefits
	Three months ended June 30,
	2012			2011			2012		2011
Service cost	$	1,939		$	1,354		$	45	$	45
Interest cost	5,426			4,587			169		201
Expected return on plan assets	(6,083		)	(4,415		)	—		—
Amortization of transition obligation	(27		)	(29		)	16		16
Amortization of prior service cost	534			412			—		—
Amortization of net actuarial losses	4,555			2,456			242		311
Net pension expense	$	6,344		$	4,365		$	472	$	573

	Pension Benefits						Other Postretirement Benefits
	Six months ended June 30,
	2012			2011			2012		2011
Service cost	$	3,884		$	2,967		$	90	$	100
Interest cost	10,953			10,391			339		424
Expected return on plan assets	(12,319		)	(10,453		)	—		—
Amortization of transition obligation	(54		)	(56		)	31		31
Amortization of prior service cost	1,075			990			—		—
Amortization of net actuarial losses	9,108			5,890			483		651
Net pension expense	$	12,647		$	9,729		$	943	$	1,206