Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 2012

Defined Benefit Pension Plans [Member]

Schedule of Components of Net Periodic Credit

The components of our net periodic defined benefit pension credit for the third quarter and first nine months of 2011 and 2012 are presented in the table below.

	Three months ended September 30,						Nine months ended September 30,
	2011			2012			2011			2012
	(In thousands)
Service cost	$	931		$	1,110		$	2,793		$	3,445
Interest cost		4,752			4,477			14,256			13,248
Expected return on plan assets		(13,365	)		(12,210	)		(39,985	)		(36,614	)
Amortization of prior service cost		308			308			924			924
Amortization of actuarial losses		2,624			4,969			7,762			13,854
Total credit	$	(4,750	)	$	(1,346	)	$	(14,250	)	$	(5,143	)

Other Postretirement Benefit Plans [Member]

Schedule of Components of Net Periodic Credit

The components of our net periodic credit related to other postretirement benefits for the third quarter and first nine months of 2011 and 2012 are presented in the table below.

	Three months ended September 30,						Nine months ended September 30,
	2011			2012			2011			2012
	(In thousands)
Service cost	$	31		$	37		$	95		$	116
Interest cost		576			512			1,723			1,526
Amortization of prior service credit		(4,043	)		(4,043	)		(12,128	)		(12,128	)
Amortization of actuarial losses		2,137			2,091			6,412			5,929
Total credit	$	(1,299	)	$	(1,403	)	$	(3,898	)	$	(4,557	)