Stock incentive plans (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Recognized stock-based compensation expense
Total stock-based compensation	$ 1,851	$ 1,245	$ 3,368	$ 1,847
Stock-based compensation expense capitalized	126		161
Network operations
Recognized stock-based compensation expense
Total stock-based compensation	351	231	639	397
Development and technology
Recognized stock-based compensation expense
Total stock-based compensation	119	142	260	99
Selling and marketing
Recognized stock-based compensation expense
Total stock-based compensation	402	340	736	458
General and administrative
Recognized stock-based compensation expense
Total stock-based compensation	$ 979	$ 532	$ 1,733	$ 893