Stock-Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-based compensation expense
Total stock-based compensation expense	$ 1,048	$ 775
Costs of revenue
Stock-based compensation expense
Total stock-based compensation expense	139	149
Selling and marketing
Stock-based compensation expense
Total stock-based compensation expense	274	216
Research and development
Stock-based compensation expense
Total stock-based compensation expense	269	131
General and administrative
Stock-based compensation expense
Total stock-based compensation expense	$ 366	$ 279