Summary of Components of Net Periodic Benefit Cost and Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Defined benefit pension plans
Net periodic benefit cost:
Service cost	$ 12,982		$ 13,285		$ 13,610
Interest cost	25,580		29,530		28,433
Expected return on plan assets	(29,786)		(31,270)		(25,714)
Amortization of prior service (credit) cost	(1,057)		(502)		1,776
Recognized actuarial loss (gain)	21,193		19,020		19,492
Settlement loss	1,835		3,534
Net periodic benefit cost	30,747		33,597		37,597
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net actuarial (gain) loss	(95,744)		27,144		62,687
Prior service cost (credit)			(11,789)		2
Amortization of prior service credit (cost)	1,057		501		(1,776)
Total recognized in other comprehensive income	(94,687)	[1]	15,856	[1]	60,913	[1]
Total recognized in net periodic benefit cost and other comprehensive income	(63,940)		49,453		98,510
Postretirement benefit plans
Net periodic benefit cost:
Service cost	82		79		73
Interest cost	1,585		1,411		1,576
Recognized actuarial loss (gain)	578		117		(48)
Net periodic benefit cost	2,245		1,607		1,601
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net actuarial (gain) loss	3,470		4,755		(1,249)
Total recognized in other comprehensive income	3,470	[1]	4,755	[1]	(1,249)	[1]
Total recognized in net periodic benefit cost and other comprehensive income	$ 5,715		$ 6,362		$ 352

[1] Amounts exclude related tax expense (benefit) of $32.5 million, $(2.3) million, and $(21.6) million, during 2013, 2012, and 2011, respectively, which are also included in other comprehensive income