Pension and Other Employee Benefits - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Loss on partial settlement of pension plan		$ 1,720
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		232	$ 95
Interest cost		1,371	1,187
Expected return on plan assets		(759)	(777)
Non-cash impact of partial pension settlement		0	(149)
Amortization of actuarial losses		450	416
Loss on partial settlement of pension plan		1,720	0
Net periodic benefit cost		3,014	772
Pension Benefits [Member] | US Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		3	3
Interest cost		948	1,016
Expected return on plan assets		(764)	(770)
Non-cash impact of partial pension settlement		0	0
Amortization of actuarial losses		186	213
Loss on partial settlement of pension plan	$ 1,700	1,720	0
Net periodic benefit cost		2,093	462
Pension Benefits [Member] | Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		229	92
Interest cost		423	171
Expected return on plan assets		5	(7)
Non-cash impact of partial pension settlement		0	(149)
Amortization of actuarial losses		264	203
Loss on partial settlement of pension plan		0	0
Net periodic benefit cost		$ 921	$ 310