Employee Benefit Plans - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Nov. 30, 2015 USD ($) Employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Conditional age-1 for availing plan		55 years
Conditional age-2 for availing plan		65 years
Conditional years of service -1 for availing plan		10 years
Conditional years of service-2 for availing plan		5 years
Fixed Income Funds
Defined Contribution Plan Disclosure [Line Items]
Targeted asset allocation percentage		40.00%
Equity Funds
Defined Contribution Plan Disclosure [Line Items]
Targeted asset allocation percentage		60.00%
Four Zero One Retirement Plan
Defined Contribution Plan Disclosure [Line Items]
Employer contributions		$ 193,000	$ 176,000
Four Zero One Retirement Plan | First 3% of Each Participant's Contributions
Defined Contribution Plan Disclosure [Line Items]
Matching contribution to defined contribution plan		100.00%
Percentage of employee's contributions		3.00%
Four Zero One Retirement Plan | Second 3% of Each Participant's Contributions
Defined Contribution Plan Disclosure [Line Items]
Matching contribution to defined contribution plan		50.00%
Percentage of employee's contributions		3.00%
Pension Plan, Defined Benefit
Defined Contribution Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 3,400,000	3,500,000
Expected employer contribution		0
Other Postretirement Benefit Plan, Defined Benefit
Defined Contribution Plan Disclosure [Line Items]
Expected employer contribution		6,000
Employer contributions		$ 8,000	$ 9,000
Other Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Age of early retirement	55 years
Minimum employee service period	10 years
Number of employees participate | Employee	5
Total cost of voluntary early retirement plan	$ 134,000