Reclassifications Out of Accumulated Other Comprehensive Income Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension and other postretirement plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of service cost, before tax	$ 1,521	$ 3,060	$ 3,456	$ 4,807
Provision for income taxes	(583)	(1,095)	(1,245)	(1,719)
Total net of tax	938	1,965	2,211	3,088
Pension and other postretirement plans | Selling, General And Administrative Expenses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of service cost, before tax	1,521	3,060	3,456	4,807
Derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustments, before tax	1,867	1,920	3,740	3,845
Provision for income taxes	(680)	(701)	(1,363)	(1,405)
Total net of tax	1,187	1,219	2,377	2,440
Derivatives | Interest Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustments, before tax	$ 1,867	$ 1,920	$ 3,740	$ 3,845