Stock incentive plans (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Recognized stock-based compensation expense
Total stock-based compensation	$ 1,517	$ 602
Stock-based compensation expense capitalized	35
Network operations
Recognized stock-based compensation expense
Total stock-based compensation	288	166
Development and technology
Recognized stock-based compensation expense
Total stock-based compensation	141	(43)
Selling and marketing
Recognized stock-based compensation expense
Total stock-based compensation	334	118
General and administrative
Recognized stock-based compensation expense
Total stock-based compensation	$ 754	$ 361