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, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Policies Employees Company	Sep. 30, 2014 USD ($) Policies Employees Company
Increase (Decrease) in Insurance Liabilities [Abstract]
Beginning balance			$ 92,337	$ 52,309
Increase in cash value of life insurance	$ 770	$ 490	2,121	1,287
Ending balance	$ 94,458	$ 53,596	94,458	53,596
End of period death benefit			$ 166,380	$ 95,896
Number of policies owned | Policies			189	133
Insurance companies used | Company			14	6
Current and former employees and directors covered | Employees			60	36