Significant Accounting Policies Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Abstract]
Restricted Cash and Cash Equivalents	$ 30.7	$ 21.7
Restricted Cash and Cash Equivalents, Current	7.9	9.3
Restricted Cash and Cash Equivalents, Noncurrent	$ 22.8	$ 12.4