Warrant Exercises (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurements [Line Items]
Gain on extinguishment of warrant liabilities	$ 73,291	$ 88,777	$ 186,897
Warrants Exercised On Jan 14
Fair Value Measurements [Line Items]
Exercise date:		--01-14	--01-14
Market price of common stock:		$ 10.64	$ 10.26
Exercise warrants:		549,300	700,000
Exercise price:		$ 3.50	$ 3.50
Remaining contractual life (years):		2 years 9 months 15 days	3 years 9 months 15 days
Dividend yield:		0.00%	0.00%
Expected volatility:		46.34%	41.12%
Risk-free interest rate:		0.90%	1.87%
Fair values:		$ 7.2301	$ 6.9482
Gain on extinguishment of warrant liabilities		48,210	131,744
Warrants Exercised On Mar 12
Fair Value Measurements [Line Items]
Exercise date:			--03-12
Market price of common stock:			$ 9.4
Exercise warrants:			6,000
Exercise price:			$ 3.50
Remaining contractual life (years):			3 years 7 months 17 days
Dividend yield:			0.00%
Expected volatility:			41.70%
Risk-free interest rate:			1.77%
Fair values:			$ 6.2975
Gain on extinguishment of warrant liabilities			3,625
Warrants Exercised On Oct 27
Fair Value Measurements [Line Items]
Exercise date:			--10-27
Market price of common stock:			$ 10.92
Exercise warrants:			35,880
Exercise price:			$ 4.80
Remaining contractual life (years):			3 years 10 months 6 days
Dividend yield:			0.00%
Expected volatility:			42.23%
Risk-free interest rate:			0.91%
Fair values:			$ 6.7131
Gain on extinguishment of warrant liabilities			21,281
Warrants Exercised On Nov 26
Fair Value Measurements [Line Items]
Exercise date:			--11-26
Market price of common stock:			$ 11.96
Exercise warrants:			211,500
Exercise price:			$ 3.50
Remaining contractual life (years):			2 years 11 months 5 days
Dividend yield:			0.00%
Expected volatility:			46.49%
Risk-free interest rate:			0.75%
Fair values:			$ 8.5925
Gain on extinguishment of warrant liabilities			28,022
Warrants Exercised On Dec 30
Fair Value Measurements [Line Items]
Exercise date:			--12-30
Market price of common stock:			$ 11.26
Exercise warrants:			10,300
Exercise price:			$ 3.50
Remaining contractual life (years):			2 years 9 months 29 days
Dividend yield:			0.00%
Expected volatility:			46.30%
Risk-free interest rate:			0.97%
Fair values:			$ 7.9760
Gain on extinguishment of warrant liabilities			2,225
Warrants Exercised On Mar 3
Fair Value Measurements [Line Items]
Exercise date:		--03-03
Market price of common stock:		$ 10.98
Exercise warrants:		20,000
Exercise price:		$ 3.50
Remaining contractual life (years):		2 years 7 months 28 days
Dividend yield:		0.00%
Expected volatility:		48.00%
Risk-free interest rate:		1.09%
Fair values:		$ 7.7083
Gain on extinguishment of warrant liabilities		8,153
Warrants Exercised On Mar 14
Fair Value Measurements [Line Items]
Exercise date:		--03-14
Market price of common stock:		$ 10.19
Exercise warrants:		28,814
Exercise price:		$ 4.80
Remaining contractual life (years):		3 years 5 months 19 days
Dividend yield:		0.00%
Expected volatility:		44.05%
Risk-free interest rate:		1.27%
Fair values:		$ 6.0599
Gain on extinguishment of warrant liabilities		5,722
Warrants Exercised On Mar 17
Fair Value Measurements [Line Items]
Exercise date:		--03-17
Market price of common stock:		$ 9.79
Exercise warrants:		74,000
Exercise price:		$ 3.50
Remaining contractual life (years):		2 years 7 months 13 days
Dividend yield:		0.00%
Expected volatility:		48.54%
Risk-free interest rate:		0.86%
Fair values:		$ 6.5324
Gain on extinguishment of warrant liabilities		(1,361)
Warrants Exercised On Apr 7
Fair Value Measurements [Line Items]
Exercise date:		--04-07
Market price of common stock:		$ 8.39
Exercise warrants:		44,850
Exercise price:		$ 4.80
Remaining contractual life (years):		3 years 4 months 28 days
Dividend yield:		0.00%
Expected volatility:		44.05%
Risk-free interest rate:		1.46%
Fair values:		$ 4.4485
Gain on extinguishment of warrant liabilities		26,531
Warrants Exercised On Dec 21
Fair Value Measurements [Line Items]
Exercise date:		--12-21
Market price of common stock:		$ 5.00
Exercise warrants:		12,500
Exercise price:		$ 3.50
Remaining contractual life (years):		1 year 10 months 10 days
Dividend yield:		1.19%
Expected volatility:		39.58%
Risk-free interest rate:		0.22%
Fair values:		$ 1.7342
Gain on extinguishment of warrant liabilities		1,522
Warrants Exercised On Feb 7
Fair Value Measurements [Line Items]
Exercise date:	--02-07
Market price of common stock:	$ 6.44
Exercise warrants:	125,000
Exercise price:	$ 3.50
Remaining contractual life (years):	1 year 8 months 23 days
Dividend yield:	0.00%
Expected volatility:	39.43%
Risk-free interest rate:	0.21%
Fair values:	$ 3.08
Gain on extinguishment of warrant liabilities	$ 73,291