Significant Accounting Policies (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) Entity	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Effective Income Tax Rate Reconciliation, Percent	26.40%	17.50%	(113.70%)
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Amount	$ 0.0	$ 16.5	$ 315.9
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 0.0	0.0	0.2
Wholly-owned bankruptcy remote special-purpose corporations | Entity	1
Interest expense net of interest income on bank deposits	$ 3.8	$ 5.7	$ 3.1
Accounting Standards Update 2016-02
Error Corrections and Prior Period Adjustments, Description	39.4
Deferred Tax Assets, Deferred Gain on Sale Leaseback Transaction	$ 4.0