Summary of Expiration Periods and Corresponding Valuation Allowances for Deferred Tax Assets related to Net Operating/Capital Loss and Tax Credit Carryforwards (Detail) (USD $)	Dec. 31, 2011
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Gross deferred tax asset	$ 7,300,000
Valuation allowance	(4,600,000)
Net deferred tax asset	2,700,000
Expiration Period 2012 - 2016
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Gross deferred tax asset, subject to expiration	500,000
Valuation allowance	(500,000)
Net deferred tax asset, subject to expiration
Expiration Period 2017 - 2026
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Gross deferred tax asset, subject to expiration	800,000
Valuation allowance
Net deferred tax asset, subject to expiration	800,000
Indefinite
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Gross deferred tax asset, not subject to expiration	6,000,000
Valuation allowance	(4,100,000)
Net deferred tax asset, not subject to expiration	$ 1,900,000