Basis of Presentation - Consolidated Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 114,434	$ 278,488	$ 286,662
Non-cash charges associated with restructuring and other, net		0	70,587
Pension and postretirement expense (benefit)		4,730	(10,117)
Deferred income taxes		7,115	14,442
As Previously Reported
Cash flows from operating activities:
Net income	104,236		257,888
Non-cash charges associated with restructuring and other, net			77,095
Pension and postretirement expense (benefit)			28,727
Deferred income taxes			(2,136)
Effect of Accounting Change
Cash flows from operating activities:
Net income	10,198		28,774
Non-cash charges associated with restructuring and other, net			(6,508)
Pension and postretirement expense (benefit)			(38,844)
Deferred income taxes			$ 16,578