Net Loss Per Share - Earnings Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Class of Stock [Line Items]
Net loss	$ (12,045)	$ (7,447)
Weighted average common shares outstanding - basic and diluted (in shares)	40,451,668	39,593,700
Basic and diluted net loss per share (in dollars per share)	$ (0.30)	$ (0.19)
Class A Common Stock
Class of Stock [Line Items]
Net loss	$ (8,496)	$ (5,110)
Weighted average common shares outstanding - basic and diluted (in shares)	28,534,236	27,166,753
Basic and diluted net loss per share (in dollars per share)	$ (0.30)	$ (0.19)
Class B Common Stock
Class of Stock [Line Items]
Net loss	$ (3,549)	$ (2,337)
Weighted average common shares outstanding - basic and diluted (in shares)	11,917,432	12,426,947
Basic and diluted net loss per share (in dollars per share)	$ (0.30)	$ (0.19)