Components of Net Periodic Expense (Benefit) of Pension Plans (Detail) (Pension Plans, Defined Benefit, USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 22,663,000	$ 22,685,000	$ 22,027,000
Expected return on plan assets	(25,008,000)	(23,304,000)	(23,832,000)
Recognized actuarial loss	11,174,000	12,616,000	14,584,000
Net periodic expense (benefit)	$ 8,829,000	$ 11,997,000	$ 12,779,000