Employee Benefit Plans (Combined Activity in Corporations Defined Benefit Pension Plans) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Fair value of plan assets at beginning of year	$ 168,450	$ 157,214	$ 163,270
Actual return on plan assets	(7,739)	23,518	5,174
Employer contributions	1,077	1,049	4,819
Benefits paid	(8,968)	(13,331)	(16,049)
Fair value of plan assets at end of year	152,820	168,450	157,214
Benefit obligation at beginning of year	182,607	176,751	194,140
Interest cost	5,898	6,189	6,958
Actuarial (gain) loss	(12,430)	12,998	(8,298)
Benefits paid	(8,968)	(13,331)	(16,049)
Benefit obligation at end of year	167,107	182,607	176,751
Funded status of the plan at end of year and accrued benefit (liability) recognized	(14,287)	(14,157)	(19,537)
Accumulated benefit obligation at end of year	$ 167,107	$ 182,607	$ 176,751