Pensions and Postretirement Benefits Plans - Defined Benefit Pension and Other Postretirement Benefits Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in benefit obligation:
Projected Benefit Obligation at January 1	$ 1,562,333	$ 1,404,422
Service cost - employer	11,046	9,768
Interest cost	56,055	62,462
Actuarial (gain)/loss	(80,426)	184,232
Benefits paid	(72,530)	(72,626)
Foreign currency translation effect	(25,127)	(25,925)
Projected Benefit Obligation at December 31	1,451,351	1,562,333	$ 1,404,422
Change in plans' assets:
Fair value of plans' assets at January 1	1,188,673	1,112,314
Actual return on plans' assets	349	121,412
Employer contribution	47,830	48,200
Benefits paid	(72,530)	(72,626)
Benefits paid	0	0
Foreign currency translation effect	(17,892)	(20,627)
Fair value of plans' assets at December 31	1,146,430	1,188,673	1,112,314
Funded status	(304,921)	(373,660)
Amounts recognized in the balance sheets:
Accrued liabilities	(300)	(300)
Postretirement benefits other than pensions	(249,650)	(264,305)
Pension benefits	(304,621)	(373,360)
Pension Benefits - Domestic [Member]
Change in benefit obligation:
Projected Benefit Obligation at January 1	1,105,100	973,276
Service cost - employer	11,037	9,760
Interest cost	40,202	42,842
Actuarial (gain)/loss	(52,663)	137,217
Benefits paid	(58,209)	(57,995)
Projected Benefit Obligation at December 31	1,045,467	1,105,100	973,276
Change in plans' assets:
Fair value of plans' assets at January 1	857,825	823,790
Actual return on plans' assets	1,095	56,284
Employer contribution	35,803	35,746
Benefits paid	(58,209)	(57,995)
Benefits paid	0	0
Fair value of plans' assets at December 31	836,514	857,825	823,790
Funded status	(208,953)	(247,275)
Amounts recognized in the balance sheets:
Accrued liabilities	(300)	(300)
Pension benefits	(208,653)	(246,975)
Pension Benefits - International [Member]
Change in benefit obligation:
Projected Benefit Obligation at January 1	457,233	431,146
Service cost - employer	9	8	8
Interest cost	15,853	19,620	15,661
Actuarial (gain)/loss	(27,763)	47,015
Benefits paid	(14,321)	(14,631)
Foreign currency translation effect	(25,127)	(25,925)
Projected Benefit Obligation at December 31	405,884	457,233	431,146
Change in plans' assets:
Fair value of plans' assets at January 1	330,848	288,524
Actual return on plans' assets	(746)	65,128
Employer contribution	12,027	12,454
Benefits paid	(14,321)	(14,631)
Benefits paid	0	0
Foreign currency translation effect	(17,892)	(20,627)
Fair value of plans' assets at December 31	309,916	330,848	288,524
Funded status	(95,968)	(126,385)
Amounts recognized in the balance sheets:
Pension benefits	(95,968)	(126,385)
Other Postretirement Benefits - All Plans [Member]
Change in benefit obligation:
Projected Benefit Obligation at January 1	278,867	252,866
Service cost - employer	2,513	2,404	3,813
Interest cost	10,320	11,305	10,791
Actuarial (gain)/loss	(13,726)	24,294
Benefits paid	(12,395)	(12,002)
Projected Benefit Obligation at December 31	265,579	278,867	$ 252,866
Change in plans' assets:
Benefits paid	(12,395)	(12,002)
Benefits paid	0	0
Funded status	(265,579)	(278,867)
Amounts recognized in the balance sheets:
Accrued liabilities	(15,929)	(14,562)
Postretirement benefits other than pensions	$ (249,650)	$ (264,305)