Goodwill and Intangible Assets (Amortization expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Amortization expense
Amortization of intangible assets	$ 1,321	$ 1,238	$ 2,551	$ 2,172
Cost of revenue
Amortization expense
Amortization of intangible assets	791	817	1,565	1,466
Research and development
Amortization expense
Amortization of intangible assets	47	50	95	90
Sales and marketing
Amortization expense
Amortization of intangible assets	$ 483	$ 371	$ 891	$ 616