Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Valuation Allowance [Line Items]
Gross deferred federal, state and local tax benefit	$ 19.4			$ 39.0
Deferred federal, state and local tax benefit	19.4			40.7
Deferred tax assets, tax deferred expense, employee compensation	(1.7)	$ (1.7)		(1.7)
Change in valuation allowance	17.8			37.7
Valuation allowance	$ 387.9			387.9		$ 336.4
Federal and State
Valuation Allowance [Line Items]
Deferred federal, state and local tax benefit			$ 15.4		$ 71.3
Change in valuation allowance			$ (2.7)	$ 39.4	$ 52.2
ASC 842
Valuation Allowance [Line Items]
Change in valuation allowance		$ 13.8