Cash Value of Life Insurance - Summary of Activity in Balance of Cash Value of Life Insurance (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) Policies Employees Company	Sep. 30, 2015 USD ($) Policies Employees Company
Increase (Decrease) in Insurance Liabilities [Abstract]
Beginning balance			$ 94,560	$ 92,337
Increase in cash value of life insurance	$ 709	$ 770	2,086	2,121
Death benefit receivable in excess of cash value			238
Death benefit receivable			(1,603)
Ending balance	$ 95,281	$ 94,458	95,281	94,458
End of period death benefit			$ 166,623	$ 166,380
Number of policies owned | Policies			187	189
Insurance companies used | Company			14	14
Current and former employees and directors covered | Employees			59	60