Stock-Based Compensation - Unrecognized cost (Details) - Restricted stock, restricted stock units, performance-based restricted stock units, cash-settled restricted stock units and cash-settled performance units $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Unrecognized compensation
Unrecognized compensation cost related to unvested awards (in dollars)	$ 16.0
Weighted-average period over which the expected unrecognized compensation cost related to unvested stock options will be recognized	1 year 9 months 18 days