Stock incentive plans (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Recognized stock-based compensation expense
Total stock-based compensation	$ 1,835	$ 1,517
Stock-based compensation expense capitalized	216	35
Network operations
Recognized stock-based compensation expense
Total stock-based compensation	347	288
Development and Technology Expense
Recognized stock-based compensation expense
Total stock-based compensation	98	141
Selling and marketing
Recognized stock-based compensation expense
Total stock-based compensation	527	334
General and administrative
Recognized stock-based compensation expense
Total stock-based compensation	$ 863	$ 754