Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 1987
Income Taxes [Line Items]
Deferred tax asset valuation allowance	$ 9,034,000	$ 8,228,000
Net deferred tax asset	0	850,000
Decrease in net deferred tax assets	0	850,000
Federal statutory rate	34.00%
Bad debt reserve balance			3,000,000
Deferred tax liability on bad debt reserve balance not required to be recorded total	1,000,000	1,000,000
General business credit	470,000	332,000
Alternative minimum tax credit	113,000	119,000
Unrecognized tax benefits if recognized would favorably affect income tax provision in future	431,000
Accrued interest related to unrecognized tax benefits	4,000	3,000
Federal
Income Taxes [Line Items]
Federal net operating loss carryforwards	11,300,000
General business credit	470,000
Operating loss carryforwards, expiration dates	2031 through 2032
California
Income Taxes [Line Items]
California net operating loss carryforwards	$ 26,900,000
Operating loss carryforwards, expiration dates	2029 through 2032