Income Taxes Amounts and Expiration Dates of Net Operating Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Taxable Income Limitation for Net Operating Loss Carryforward		80.00%
Net Operating Loss Subject to Taxable Income Limitation		$ 54.5
State NOL and tax credit carryforwards		114.7
State net operating loss valuation allowance		(98.8)	$ (82.3)
U.S. NOL(1)	[1]	182.1
U.S. alternative minimum tax credit		37.1	$ 126.0
Total NOL and tax credit carryforwards		$ 337.7
State [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards Minimum Expiration Date		2020
Operating Loss Carryforwards Maximum Expiration Date		2038
U.S. (Federal) [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards Minimum Expiration Date		2037
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount		$ 3.8
2019 [Member]
Operating Loss Carryforwards [Line Items]
U.S. alternative minimum tax credit		37.5
Future Years [Member]
Operating Loss Carryforwards [Line Items]
U.S. alternative minimum tax credit		$ 74.6

[1] Federal NOL's created in tax years beginning after December 31, 2017 can be carried forward indefinitely under the Tax Legislation (limited to 80% of taxable income computed without the NOL deduction). Of the Company's U.S. NOL, $54.5 million has an indefinite carryforward period but its use is limited to 80% of taxable income.