Pension and Profit Sharing Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Contributions to the plan	$ 0	$ 0
Defined benefit plan pension obligation retirement benefit percentage	53.00%
Defined benefit plan pension obligation, loss on settlement	$ 1,546,000
Weighted average final maturities of debt securities held in the pension plan, Years	6 years 10 months 28 days
Level 3 securities	0
Common stock value	$ 678,000	663,000
Vesting period	6 years
Defined contribution plan cost	$ 7,049,000	4,735,000	$ 3,221,000
Employee deferrals	4.00%
Employee compensation	5.00%
Directors' fees	100.00%
Profit Sharing Plan's Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock value	$ 68,855,000	55,796,000
Pension Plan's Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock value	3,373,000	2,776,000
Safe Harbor 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan cost	$ 2,588,000	$ 2,392,000	$ 2,331,000
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average final maturities of debt securities held in the pension plan, Years	2 years 6 months 14 days
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average final maturities of debt securities held in the pension plan, Years	18 years 9 months 3 days