Pension and Postretirement Benefits - Net Periodic Cost (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Domestic Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 4,991	$ 5,276	$ 14,973	$ 15,828
Expected return on plan assets	(4,907)	(5,002)	(14,721)	(15,006)
Net periodic (benefit) cost	84	274	252	822
TCN Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	290	338	870	1,014
Expected return on plan assets	(345)	(397)	(1,035)	(1,191)
Net periodic (benefit) cost	$ (55)	$ (59)	$ (165)	$ (177)