Stock-based Awards - Stock Compensation Costs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock based Compensation Cost
Total stock-based compensation expense	$ 9,440	$ 1,968	$ 20,978	$ 5,584
Amount capitalized to internal software use	331	112	947	366
Total stock-based compensation cost	9,771	2,080	21,925	5,950
Cost of revenue
Stock based Compensation Cost
Total stock-based compensation expense	134	28	297	81
Sales and marketing
Stock based Compensation Cost
Total stock-based compensation expense	1,413	591	3,757	1,696
Technology and development
Stock based Compensation Cost
Total stock-based compensation expense	2,069	362	3,933	1,143
General and administrative
Stock based Compensation Cost
Total stock-based compensation expense	$ 5,824	$ 987	$ 12,991	$ 2,664