Employee Benefit Plans - Components of Net Periodic Benefit (Income) Cost (Detail) - Pension Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,746	$ 8,562	$ 7,824
Interest cost	104,485	98,088	102,465
Expected return on plan assets	(156,832)	(150,130)	(144,746)
Amortization of prior service credit	(432)	(565)	(1,890)
Amortization of actuarial loss	31,641	38,197	26,791
Net periodic benefit income	$ (13,392)	$ (5,848)	$ (9,556)