Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2013

Employee Benefit Plans

Schedule of net periodic (benefit) cost

	Three months ended March 31,
	Defined Benefit Pension Plan						Post-Retirement Medical Plan						Supplemental Executive Retirement Plan
	2013			2012			2013			2012			2013		2012
Components of net periodic cost (benefit):
Service cost	$	1,259		$	1,039		$	232		$	184		$	251	$	248
Interest cost	5,173			5,214			123			134			637		728
Expected return on plan assets	(6,029		)	(5,427		)	—			—			—		—
Amortization of transition obligation	—			—			—			—			—		—
Amortization of unrecognized prior service cost	13			13			(412		)	(412		)	233		233
Amortization of loss from earlier periods	3,894			2,446			(103		)	(134		)	325		159
Net periodic cost (benefit)	$	4,310		$	3,285		$	(160	)	$	(228	)	$	1,446	$	1,368

Schedule of contributions to the Defined Benefit Pension Plan and payments made to the Post-Retirement Medical Plan and the Supplemental Executive Retirement Plan

	Three months ended March 31,
	2013		2012
Contributions to the Defined Benefit Pension Plan	$	—	$	3,244
Payments to the Post-Retirement Medical Plan	153		174
Payments to the Supplemental Executive Retirement Plan	930		698