Pension and Other Postretirement Benefits - Change in Benefit Obligation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	$ (258,423)	$ (263,876)
Service cost	(5,453)	(5,554)	(5,423)
Interest cost	(10,757)	(9,310)	(10,510)
Participant contributions	(109)	(105)
Plan amendments	0	(56)
Actuarial gain (loss)	(28,971)	8,147
Acquisitions	(25,283)	0
Curtailments	359	0	0
Foreign currency exchange rate changes	13,708	(1,826)
Benefits paid	14,590	14,157
Benefit obligation, end of year	(300,339)	(258,423)	(263,876)
Other Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	(46,614)	(51,772)
Service cost	(49)	(125)	(116)
Interest cost	(1,647)	(1,910)	(2,077)
Participant contributions	(7)	(11)
Plan amendments	0	0
Actuarial gain (loss)	4,392	2,096
Acquisitions	0	0
Curtailments	0	0
Foreign currency exchange rate changes	2,704	2,681
Benefits paid	2,052	2,427
Benefit obligation, end of year	$ (39,169)	$ (46,614)	$ (51,772)