Pension plans and other postretirement benefits (Tables)

9 Months Ended

Sep. 30, 2012

Net Periodic Benefit Cost for Defined Benefit Plans

The Company provides defined benefit pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. Net periodic defined benefit cost for defined benefit plans consisted of the following:

	Pension benefits						Other postretirement benefits
	Three months ended September 30
	2012			2011			2012		2011
				(in thousands)
Service cost	$	7,387			8,557			167		148
Interest cost on projected benefit obligation		15,509			16,155			934		1,038
Expected return on plan assets		(17,627	)		(16,718	)		—		—
Amortization of prior service cost		(1,640	)		(1,640	)		5		27
Amortization of net actuarial loss		9,291			5,132			133		9
Net periodic benefit cost	$	12,920			11,486			1,239		1,222
	Pension benefits						Other postretirement benefits
	Nine months ended September 30
	2012			2011			2012		2011
				(in thousands)
Service cost	$	22,162			20,270			501		388
Interest cost on projected benefit obligation		46,527			42,391			2,803		2,722
Expected return on plan assets		(52,883	)		(43,981	)		—		—
Amortization of prior service cost		(4,919	)		(4,919	)		15		81
Amortization of net actuarial loss		27,874			15,397			398		27
Net periodic benefit cost	$	38,761			29,158			3,717		3,218