Share Incentive Plans, Compensation Expense Related to Options (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Compensation Expense [Abstract]
Compensation expense related to options	$ 0.5	$ 0.2	$ 1.2	$ 0.6
Unrecognized compensation expense related to options	$ 1.5		$ 1.5
Period over which unrecognized compensation expense will be expensed			2 years 1 month 24 days