Reconciliations of Benefit Obligation, Plan Assets of Pension Plans and Funded Status of Plans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in plan assets
Fair value of plan assets end of year	$ 419,771	$ 385,483
Funded status
Net amount recognized	241,800
Pension benefits
Change in benefit obligation
Benefit obligation beginning of year	586,808	552,309
Service cost	12,466	11,588	12,334
Interest cost	32,768	31,671	32,612
Amendments		(281)
Settlements	(257)	(104)
Actuarial (gain) loss	62,751	24,677
Translation (gain) loss	(2,477)	(4,208)
Benefits paid	(30,488)	(28,844)
Benefit obligation end of year	661,571	586,808	552,309
Change in plan assets
Fair value of plan assets beginning of year	385,483	329,188
Actual gain (loss) return on plan assets	27,971	35,495
Company contributions	37,097	49,840
Settlements	(257)	(104)
Translation gain (loss)	(35)	(92)
Benefits paid	(30,488)	(28,844)
Fair value of plan assets end of year	419,771	385,483	329,188
Funded status
Plan assets less than benefit obligation	(241,800)	(201,325)
Net amount recognized	(241,800)	(201,325)
Post-retirement
Change in benefit obligation
Benefit obligation beginning of year	33,715	35,301
Service cost	180	200	214
Interest cost	1,889	2,013	2,377
Actuarial (gain) loss	2,494	(647)
Benefits paid	(3,197)	(3,152)
Benefit obligation end of year	35,081	33,715	35,301
Change in plan assets
Company contributions	3,197	3,152
Benefits paid	(3,197)	(3,152)
Funded status
Plan assets less than benefit obligation	(35,081)	(33,715)
Net amount recognized	$ (35,081)	$ (33,715)