Amount of Income Tax (Expense) Benefit Allocated To Each Component of Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair value adjustment to cash flow hedges, before tax	$ 0	$ 0	$ (882)
Reclassification adjustment for cash flow hedge amounts included in net earnings, before tax	6,314	11,657	19,619
Adjustment for funded status of pension and postretirement benefit plans, before tax	(40,414)	(88,033)	5,683
Amortization of pension and postretirement plan actuarial loss and prior service cost, before tax	19,774	12,485	6,371
Total other comprehensive income (loss), before tax	(14,326)	(63,891)	30,791
Fair value adjustment to cash flow hedges, tax (expense) benefit	0	0	401
Reclassification adjustment for cash flow hedge amounts included in net earnings, tax (expense) benefit	(2,498)	(4,506)	(8,910)
Adjustment for funded status of pension and postretirement benefit plans, tax (expense) benefit	15,960	33,667	(2,482)
Amortization of pension and postretirement plan actuarial loss and prior service cost, tax (expense) benefit	(7,809)	(4,775)	(2,781)
Total other comprehensive income (loss), tax (expense) benefit	5,653	24,386	(13,772)
Fair value adjustment to cash flow hedges, net of tax	0	0	(481)
Reclassification adjustment for cash flow hedge amounts included in net earnings, net of tax	3,816	7,151	10,709
Adjustment for funded status of pension and postretirement benefit plans	(24,454)	(54,366)	3,201
Amortization of pension and postretirement plan actuarial loss and prior service cost, net of tax	11,965	7,710	3,590
Total other comprehensive income (loss), net of tax	$ (8,673)	$ (39,505)	$ 17,019