Employee Benefit Plans (Net Periodic Benefit Cost (Benefit)) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Expected return on plan assets, net of expenses	$ (11,117)	$ (11,558)	$ (11,932)
Interest cost on projected benefit obligation	6,189	6,958	8,210
Net amortization and deferral	5,429	6,247	6,995
SERP settlement costs	0	1,027	0
Net periodic expense (benefit)	$ 501	$ 2,674	$ 3,273