Stockholders' Equity and Share-Based Compensation - Allocation of Stock Compensation Expense (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 9,019,000	$ 8,115,000	$ 5,572,000
Unrecognized share-based compensation expense	21,400,000
Unrecognized compensation cost, period for recognition	2 years 6 months 0 days
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	838,000	755,000	333,000
Product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	1,813,000	1,763,000	1,136,000
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	3,086,000	2,545,000	1,672,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	3,220,000	3,093,000	2,428,000
Business consolidation, transaction and restructuring costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 62,000	$ (41,000)	$ 3,000