Stock Compensation (Tables)

12 Months Ended

Dec. 31, 2012

Stock Compensation

Schedule of valuation assumptions used for valuation of fair value of stock compensation granted

	Employee Stock Options For the Year Ended									Employee Stock Purchase Plan For the Year Ended
	December 31,									December 31,
	2012			2011			2010			2012			2011			2010
Average risk-free interest rates		0.49	%		0.97	%		1.10	%		0.28	%		0.53	%		0.66	%
Average expected life (in years)		3.90			3.30			2.97			0.50			0.50			0.50
Volatility		57	%		71	%		74	%		50	%		36	%		46	%
Weighted-average fair value (in dollars)		7.73			7.33			5.23			3.68			1.28			0.64