Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense

Total stock-based compensation expense recognized in our consolidated statements of operations includes amounts related to stock options, restricted stock units, and employee stock purchase plans and was as follows (in thousands):

	Quarters Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Total stock-based compensation expense	$	1,673	$	2,020	$	3,010	$	4,058

Weighted-Average Assumptions Used to Determine Fair Value of Options Granted

The fair value of options granted determined using the Black-Scholes model used the following weighted-average assumptions:

	Quarters Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Expected dividend yield	0	%	0	%	0	%	0	%
Risk-free interest rate	1.20	%	0.52	%	1.19	%	0.55	%
Expected life (years)	3.8		5.4		3.8		4.3
Volatility	40	%	48	%	40	%	48	%