Cash Value of Life Insurance - Summary of Activity in Balance of Cash Value of Life Insurance (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Policies Employees Company	Jun. 30, 2015 USD ($) Policies Employees Company
Increase (Decrease) in Insurance Liabilities [Abstract]
Beginning balance			$ 94,560	$ 92,337
Increase in cash value of life insurance	$ 681	$ 675	1,377	1,350
Death benefit receivable in excess of cash value			238
Death benefit receivable			(1,603)
Ending balance	$ 94,572	$ 93,687	94,572	93,687
End of period death benefit			$ 166,632	$ 165,728
Number of policies owned | Policies			187	189
Insurance companies used | Company			14	14
Current and former employees and directors covered | Employees			59	60