Pension Plan and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2012

Pension Plan And Other Postretirement Benefits [Abstract]

Net Periodic Pension and Other Postretirement Benefit Costs

	Pension Benefits
	For the three months ended				For the six months ended
	June 30,				June 30,
	2012		2011		2012		2011
	(in thousands)
Service cost	$	2,735	$	2,331	$	5,471	$	4,662
Interest cost		1,012		918		2,025		1,835
Expected return on plan assets		(1,356)		(1,100)		(2,713)		(2,199)
Amortization of prior service cost		72		86		143		172
Amortization of net loss		305		214		610		428
Net periodic benefit cost	$	2,768	$	2,449	$	5,536	$	4,898
	Postretirement Benefits
	For the three months ended				For the six months ended
	June 30,				June 30,
	2012		2011		2012		2011
	(in thousands)
Service cost	$	458	$	339	$	916	$	677
Interest cost		99		63		199		126
Amortization of transition obligation		16		16		32		32
Amortization of prior service cost		4		3		7		7
Amortization of net loss		23		3		46		6
Net periodic benefit cost	$	600	$	424	$	1,200	$	848