Employee Benefit Plans (Net Periodic Cost) (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Service costs	$ 184		$ 260	$ 551	$ 781
Interest costs	2,086		5,999	11,185	18,000
Settlement costs	152,388	$ 66,300	0	152,388	0
Expected return on plan assets	0		(3,083)	(4,740)	(9,250)
Amortization of net actuarial loss	1,958		7,043	15,792	21,153
Amortization of prior service credit	(1,045)		(1,211)	(3,268)	(3,633)
Net periodic cost	$ 155,571		$ 9,008	$ 171,908	$ 27,051