Benefit Plans and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2012

Benefit Plans and Other Postretirement Benefits

Schedule of components of net pension expense

	Pension Benefits						Other Postretirement Benefits
	Three months ended March 31,
	2012			2011			2012		2011
Service cost	$	1,945		$	1,613		$	45	$	55
Interest cost	5,527			5,804			169		223
Expected return on plan assets	(6,236		)	(6,038		)	—		—
Amortization of transition obligation	(27		)	(27		)	16		15
Amortization of prior service cost	541			578			—		—
Amortization of net actuarial losses	4,553			3,434			242		340
Net pension expense	$	6,303		$	5,364		$	472	$	633