Income Tax Matters, Reconciliation Between Income Tax Provision and Statutory Income Tax Provision Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation between income tax provision and statutory income tax provision:
Amount of federal income tax provision based on the statutory rate	$ (25.2)	$ (46.5)	$ (51.5)
Decrease (increase) in federal valuation allowances	1.7	0.5	(0.3)
Non-deductible compensation (expense) benefit	(0.6)	(2.3)	0.3
Non-deductible expense	(1.5)	0.0	(0.3)
State income taxes, net of federal benefit	(2.5)	(4.3)	(4.2)
Foreign income tax (expense) benefit	(0.5)	(0.1)	0.5
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	0.4	(5.9)	0.0
Effective Income Tax Rate Reconciliation, Tax Settlement, Foreign, Amount	0.1	29.0	0.0
Income tax provision	(28.3)	(87.6)	(55.5)
State and Local Jurisdiction [Member]
Reconciliation between income tax provision and statutory income tax provision:
Decrease (increase) in federal valuation allowances	2.9	2.2	(0.3)
State and tax expense (benefit) before adjustments	4.5	4.0	4.1
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ (0.9)	$ (2.5)	$ 0.2