Employee Benefit Plans - Components of Net Periodic Benefit (Income) Cost for the Pension Plans (Detail) - Pension Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8,562	$ 7,824	$ 19,083
Interest cost	98,088	102,465	89,408
Expected return on plan assets	(150,130)	(144,746)	(133,816)
Amortization of prior service credit	(565)	(1,890)	(7,538)
Amortization of actuarial loss	38,197	26,791	83,934
Net periodic benefit (income) cost	$ (5,848)	$ (9,556)	$ 51,071