Significant Accounting Policies (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Entity	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Error Corrections and Prior Period Adjustments, Description	40
Deferred Tax Assets, Deferred Gain on Sale Leaseback Transaction	$ 4.0			$ 4.0
Effective Income Tax Rate Reconciliation, Percent	17.50%	(113.70%)	31.30%
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Amount	$ 16.5	$ 315.9	$ 0.0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 0.0	0.2	0.0
Wholly-owned bankruptcy remote special-purpose corporations | Entity	1
Interest expense net of interest income on bank deposits	$ 5.7	$ 3.1	$ 1.9