Stock-Based Compensation and Employee Benefit Plan - Stock Options (Additional Information) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Goods and Nonemployee Services Transaction [Abstract]
Stock options exercised	$ 3,900,000	$ 2,200,000	$ 5,900,000	$ 2,500,000
Granted options (in shares)	313,909	1,519,861	423,854	1,681,673
Unrecognized compensation cost related to unvested stock options	$ 52,600,000		$ 52,600,000
Expense expected to be recognized over remaining weighted-average period			2 years 1 month 13 days
Excess tax benefits	0	$ 0	$ 0	$ 0
Employee Stock Option
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Allocated share-based compensation expense	7,600,000	7,400,000	15,400,000	13,900,000
Employee stock-based compensation cost capitalized	0	0	0	0
Nonemployee Stock Option
Share-based Goods and Nonemployee Services Transaction [Abstract]
Non-employee share-based compensation expense	200,000	100,000	400,000	800,000
Non-employee stock-based compensation cost capitalized	$ 0	$ 0	$ 0	$ 0