Pensions and Other Post-retirement Benefits - Schedule of Defined Benefit Pension Plans and Other Postretirement Benefits Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Funded Status
Noncurrent assets	$ 83,060	$ 62,916
Noncurrent liabilities	(170,773)	(157,927)
Pension Benefits
Change in Benefit Obligations
Benefit obligations at January 1	503,997	491,180
Service cost	11,023	10,417	$ 11,517
Interest cost	18,450	18,752	18,314
Participant contributions	100	100
Plan amendments	0	(1,092)
Actuarial (gains) losses	27,967	9,123
Benefits paid	(28,953)	(19,550)
Curtailments	0	163
Settlements	(573)	(381)
Special termination charge	11,384	0
Currency translation	16,990	(4,389)
Benefit obligations at December 31	560,385	503,997	491,180
Change in Plan Assets
Fair value of plan assets at January 1	433,262	419,088
Actual return on plan assets	81,192	31,418
Employer contributions	4,094	3,878
Participant contributions	100	100
Settlements	(573)	(381)
Benefits paid	28,953	19,550
Administrative Expenses Paid	(222)	0
Currency translation	3,777	(1,291)
Fair value of plan assets at December 31	492,677	433,262	419,088
Funded Status
Funded status at December 31	(67,708)	(70,735)
Unrecognized transition losses	6	8
Unrecognized net actuarial losses	162,032	187,738
Net amount recognized	93,566	116,365
Noncurrent assets	83,060	62,916
Current liabilities	(5,126)	(4,620)
Noncurrent liabilities	(145,642)	(129,031)
Net amount recognized	(67,708)	(70,735)
Amounts Recognized in Accumulated Other Comprehensive Loss
Net actuarial losses	162,032	187,738
Prior service (credit) cost	(764)	(646)
Unrecognized net initial obligation	6	8
Total (before tax effects)	161,274	187,100
Accumulated Benefit Obligations for all Defined Benefit Plans	525,385	465,448
Other Benefits
Change in Benefit Obligations
Benefit obligations at January 1	23,680	22,974
Service cost	403	426	444
Interest cost	882	946	863
Participant contributions	264	222
Plan amendments	(1,694)	(400)
Actuarial (gains) losses	1,465	1,285
Benefits paid	(2,973)	(1,773)
Curtailments	0	0
Settlements	0	0
Special termination charge	0	0
Currency translation	0	0
Benefit obligations at December 31	22,027	23,680	22,974
Change in Plan Assets
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Employer contributions	2,709	1,551
Participant contributions	264	222
Settlements	0	0
Benefits paid	2,973	1,773
Administrative Expenses Paid	0	0
Currency translation	0	0
Fair value of plan assets at December 31	0	0	$ 0
Funded Status
Funded status at December 31	(22,027)	(23,680)
Unrecognized transition losses	0	0
Unrecognized net actuarial losses	5,007	3,643
Net amount recognized	(19,348)	(21,542)
Noncurrent assets	0	0
Current liabilities	(1,584)	(1,638)
Noncurrent liabilities	(20,443)	(22,042)
Net amount recognized	(22,027)	(23,680)
Amounts Recognized in Accumulated Other Comprehensive Loss
Net actuarial losses	5,007	3,643
Prior service (credit) cost	(2,328)	(1,505)
Unrecognized net initial obligation	0	0
Total (before tax effects)	2,679	2,138
Accumulated Benefit Obligations for all Defined Benefit Plans	$ 0	$ 0