Fair Value Measurements (Change in Fair Value) (Details) - Conversion of preferred stock warrants - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	$ 0	$ 5,451
Change in value of preferred stock warrants recorded in other expense, net	0	0	732
Net exercise of preferred stock warrant and conversion of preferred stock warrant to common stock warrant	0	0	(6,183)
Ending balance	$ 0	$ 0	$ 0