Restructuring (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.0
Reversal of non-cash-stock-based compensation expense	3.7
Payments for restructuring	5.4
Restructuring costs	7.7
Research and development [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.6
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.4
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7.7
Accrued Payroll
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2.3