Acquisitions - Pro forma (unaudited) (Details) - Peak Pace Solutions, SinfoniaRx And Mediture - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Acquisition
Revenue	$ 57,343	$ 43,572	$ 159,764	$ 126,326
Net income (loss)	$ 11,278	$ (1,216)	$ (35,816)	$ (5,753)
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)	$ 0.59	$ (0.07)	$ (1.88)	$ (0.34)
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)	$ 0.51	$ (0.07)	$ (1.88)	$ (0.34)