Components of Pension Benefits Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12,741	$ 12,830	$ 11,271
Interest cost	31,636	32,933	31,844
Expected return on assets	(44,752)	(42,186)	(40,213)
Actuarial loss	72,550	88,809	29,512
Amortization of net transition asset			(9)
Amortization of prior service benefit	(757)	(953)	(986)
Benefits expense	71,418	91,433	31,419
Weighted-average assumption percentages:
Discount rate	5.04%	5.40%	5.77%
Expected return on plan assets	8.19%	8.19%	8.19%
Domestic Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	11,274	11,169	9,577
Interest cost	29,843	30,945	29,934
Expected return on assets	(44,342)	(41,776)	(39,903)
Actuarial loss	65,603	88,091	29,556
Amortization of net transition asset			(9)
Amortization of prior service benefit	(812)	(1,009)	(1,038)
Benefits expense	$ 61,566	$ 87,420	$ 28,117
Weighted-average assumption percentages:
Discount rate	5.07%	5.45%	5.86%
Expected return on plan assets	8.25%	8.25%	8.25%