Employee Benefit Plans - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2017 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Minimum age of full-time employees	21 years
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
Pension Plan, Defined Benefit
Defined Contribution Plan Disclosure [Line Items]
Expected employer contribution	$ 0
Other Postretirement Benefit Plan, Defined Benefit
Defined Contribution Plan Disclosure [Line Items]
Expected employer contribution	3,000
Employer contribution	$ 3,000