Stock-Based Compensation and Employee Benefit Plans (Summary of Option Activity) (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Number of Options
Beginning balance (in shares) | shares	7,932,782
Exercised (in shares) | shares	(456,256)
Expired (in shares) | shares	(535,557)
Ending balance (in shares) | shares	6,940,969
Exercisable, number of options (in shares) | shares	6,124,370
Vested or expected to vest, number of options (in shares) | shares	6,898,053
Weighted- Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 5.86
Exercised (in dollars per share) | $ / shares	2.30
Expired (in dollars per share) | $ / shares	11.21
Ending balance (in dollars per share) | $ / shares	5.68
Exercisable, weighted-average exercise price (in dollars per share) | $ / shares	5.68
Vested or expected to vest, weighted-average exercise price (in dollars per share) | $ / shares	$ 5.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted-average remaining contractual term	5 years 3 months 19 days
Outstanding, aggregate intrinsic value | $	$ 6,810
Exercisable, weighted-average remaining contractual term	4 years 10 months 24 days
Exercisable, aggregate intrinsic value | $	$ 6,810
Vested or expected to vest, weighted-average remaining contractual term	5 years 3 months 19 days
Vested or expected to vest, aggregate intrinsic value | $	$ 6,810