Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plans [Member]
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 1,413	$ 1,235	$ 1,530
Interest cost	16,240	19,871	24,600
Expected return on plan assets	(25,300)	(27,337)	(28,301)
Amortization of:
Prior service cost	30	2,369	2,376
Net actuarial loss (gain)	10,141	3,888	5,440
Settlement loss (gain)	807
Net periodic benefit cost (credit)	3,331	26	5,645
Actual return on plan assets	43,624	119,287	9,873
Employer contributions	16,844	11,343	39,301
Benefits paid	42,022	29,384	32,321
Net actuarial (gain) loss	(17,357)	51,626	(4,650)
Reclassification of prior service (cost) credit to earnings	(30)	(2,369)	(2,376)
Reclassification of actuarial gain (loss) to earnings	(10,141)	(3,888)	(5,440)
Currency translation and other adjustments	18,778	(20,309)	(11,582)
Total recognized in AOCI	(8,750)	25,060	(24,048)
Net amount recognized in total periodic benefit cost and AOCI	$ (5,419)	25,086	(18,403)
Medical Plan [Member]
Components of Net Periodic Benefit Cost (Credit):
Service cost		11	27
Interest cost		167	179
Amortization of:
Net actuarial loss (gain)		(185)
Settlement loss (gain)		(1,788)
Net periodic benefit cost (credit)		(1,795)	206
Employer contributions		3,289	276
Benefits paid		3,289	276
Net actuarial (gain) loss		(1,638)	(695)
Reclassification of actuarial gain (loss) to earnings		1,973
Total recognized in AOCI		335	(695)
Net amount recognized in total periodic benefit cost and AOCI		$ (1,460)	$ (489)