Line of Credit - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Total availability under line of credit agreement	$ 10,000,000.0
Borrowings under the line of credit agreement	0	$ 0
Letters of credit outstanding amount	2,700,000
Available borrowing under letter of credit	$ 7,300,000
Maximum ratio of total liabilities to tangible net worth	1
Minimum required fixed coverage charge ratio	1.25
Period used for calculating ratios	12 months
Company's tangible net worth ratio	1.02
Fixed coverage charge ratio	2.30
LIBOR
Debt Instrument [Line Items]
Line of credit interest rate	1.50%
Prime Rate
Debt Instrument [Line Items]
Line of credit interest rate	0.75%