Share-Based Compensation - Unrecognized Compensation Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 85,599
Stock options
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 10,714
Average Expected Recognition Period - in Years	2 years 6 months 29 days
Restricted stock units and awards
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 74,885
Average Expected Recognition Period - in Years	2 years 8 months 16 days