Pension and Profit Sharing Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Participants shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) Participants
Defined Benefit Plan Disclosure [Line Items]
Contributions to the plan	$ 500,000	$ 500,000
Loss from partial settlement of pension plan	267,000		$ 2,909,000
Benefits paid out of pension plan assets to plan participants	$ 649,000		$ 10,626,000
Number of participants reduced | Participants	38		335
Weighted average final maturities of debt securities held in the pension plan, Years	5 years 29 days
Level 3 securities | shares	0
Common stock value	$ 661,000	660,000
Vesting period	6 years
Defined contribution plan cost	$ 3,221,000	5,455,000	$ 5,324,000
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	$ 60,270,000	41,599,000
Pension Plan's Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock value	2,786,000	1,859,000
Safe Harbor 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan cost	$ 2,331,000	$ 2,043,000	$ 1,699,000
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 7 days
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average final maturities of debt securities held in the pension plan, Years	11 years 4 months 2 days