Restricted Stock, Stock Options and Other Stock Plans - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Dec. 14, 2004	Dec. 31, 2014	Dec. 31, 2013	Nov. 30, 2014	Apr. 27, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan stock option expiration period	10 years
Weighted-average remaining contractual term of unexercised stock options		6 years 8 months 12 days	7 years 2 months 12 days
Unrecognized compensation cost related to stock issuances		$ 500,000	$ 800,000
Shares purchased under repurchase program, shares		95,400
Shares purchased under repurchase program, amount		103,000
Share repurchase program, commissions		$ 2,000
Remaining common stock available for repurchase under share repurchase program		2,900,000
Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized increase in number of shares		2,500,000			7,100,000
Shares issued		750
Description of additional shares authorized for issuance under long-term compensation plan		The Plan provided an initial authorization of 2.5 million shares of Class A common stock for issuance and allows an automatic annual increase equal to the lesser of (i) 3% of the Class A common stock outstanding (ii) 750 shares or (iii) such lesser amount as may be determined by the Company's board of directors.
Shares available for issuance under long-term compensation plan		2,200,000
Percentage of additional shares authorized issuable under long-term compensation plan		3.00%
New share repurchase program, shares authorized to repurchase				3,000,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan vesting period	1 year
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan vesting period	5 years