Stock-Based Compensation - Schedule of Share-based Compensation, Stock Options, Activity (Details) - Employee Stock Option [Member]	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Number of Shares, Outstanding at beginning of period | shares	6,499,885
Number of Shares, Granted | shares	767,201
Number of Shares, Exercised | shares	(292,417)	[1]
Number of Shares, Forfeited | shares	(370,208)
Number of Shares, Outstanding at end of period | shares	6,604,461
Number of Shares, Options exercisable | shares	4,567,527
Weighted Average Exercise Price, Outstanding at beginning of year	$ 14.02
Weighted Average Exercise Price, Granted	14.36
Weighted Average Exercise Price, Exercised	3.99	[1]
Weighted Average Exercise Price, Forfeited	7.81
Weighted Average Exercise Price, Outstanding at end of year	14.30
Weighted Average Exercise Price, Options exercisable	12.11
Weighted-average fair value of options granted during the period	$ 10.28

[1] The number of exercised options includes shares withheld on behalf of employees to satisfy minimum statutory tax withholding requirements.