Employee Benefit Plans (Pension Benefit Plan) - Components of Net Periodic Pension Cost and Amounts Recognized Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net periodic benefit cost:
Service cost	$ 1,193	$ 1,260	$ 1,211
Interest cost	727	607	720
Expected return on plan assets	(1,548)	(1,267)	(1,057)
Amortization of actuarial losses	247	309	175
Net periodic benefit cost	619	909	1,049
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net actuarial (gain) loss	5,638	(654)	1,782
Amortization of actuarial losses	(196)	(406)	(156)
Amount recognized in other comprehensive income (loss)	5,442	(1,060)	1,626
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$ 6,061	$ (151)	$ 2,675