Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2012

Employee Benefit Plans [Abstract]

Components of Net Periodic Benefit Cost

	Pension Benefits						Other Post-retirement Benefits
	2012			2011			2012			2011
	(in thousands)
Service cost	$	3,833		$	3,187		$	—		$	—
Interest cost		25,144			24,064			67			117
Expected return on plan assets		(32,094	)		(31,053	)		—			—
Amortization of prior service credit		(1,748	)		(1,750	)		(233	)		(265	)
Amortization of actuarial loss		17,755			12,671			317			433
Net periodic benefit cost	$	12,890		$	7,119		$	151		$	285