Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Summary of Significant Accounting Policies [Abstract]

Assumptions in Black-Scholes valuation models

	Years Ended December 31,
	2012	2011	2010
Risk-free interest rates	0.33% – 0.83%	0.86% – 2.30%	0.80% – 2.65%
Dividend yields	—	—	—
Volatility factor of expected market price	.530 – .710	.732 – .797	.795 – 1.036
Weighted-average expected term of option	3.8 – 5 years	3.7 – 5 years	3.9 – 4.9 years
Forfeiture rate	—	—	—