Note 16. Financial Statements for Guarantors of Senior Notes Balance Sheets for Guarantors of Senior Notes (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents, at Carrying Value	$ 166.2	$ 179.2
Accounts Receivable, after Allowance for Credit Loss	260.1	276.6
Income Taxes Receivable	14.7	40.4
Inventory, Net	433.4	524.7
Property, Plant and Equipment, Net	7,110.6	6,334.4
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0	0.0
Restricted Cash and Cash Equivalents	111.4	171.6
Goodwill and Other Assets	605.0	462.3
Assets	8,701.4	7,989.2
Accounts Payable	203.9	212.1
Accrued Liabilities	342.1	368.3
Recourse And Non-Recourse Debt And Capital Lease Obligations	4,881.9	4,029.2
Deferred Gain on Sale of Property	0.0	17.7
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	798.3	743.1
Due to Affiliate	0.0	0.0
Other Liabilities	96.3	56.8
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,378.9	2,562.0	$ 4,858.0	$ 4,311.1
Liabilities and Equity	8,701.4	7,989.2
Consolidation, Eliminations [Member]
Cash and Cash Equivalents, at Carrying Value	(25.3)	(38.7)
Accounts Receivable, after Allowance for Credit Loss	(0.9)	0.0
Income Taxes Receivable	0.0	0.0
Inventory, Net	(0.1)	(2.0)
Property, Plant and Equipment, Net	(843.7)	(723.6)
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(8,083.2)	(8,081.2)
Restricted Cash and Cash Equivalents	25.3	38.7
Goodwill and Other Assets	(38.9)	(38.9)
Assets	(8,966.8)	(8,845.7)
Accounts Payable	(1.1)	(0.4)
Accrued Liabilities	(0.7)	(0.1)
Recourse And Non-Recourse Debt And Capital Lease Obligations	0.0	0.0
Deferred Gain on Sale of Property		0.0
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	(38.1)	(38.6)
Due to Affiliate	(1,871.8)	(1,750.7)
Other Liabilities	0.0	0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(7,055.1)	(7,055.9)
Liabilities and Equity	(8,966.8)	(8,845.7)
Parent Company [Member] | Reportable Legal Entities [Member]
Cash and Cash Equivalents, at Carrying Value	155.1	154.7
Accounts Receivable, after Allowance for Credit Loss	1.3	12.5
Income Taxes Receivable	14.6	40.4
Inventory, Net	0.0	0.0
Property, Plant and Equipment, Net	37.8	42.0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	4,600.0	4,505.2
Restricted Cash and Cash Equivalents	0.0	0.0
Goodwill and Other Assets	190.9	205.1
Assets	4,999.7	4,959.9
Accounts Payable	5.3	8.6
Accrued Liabilities	166.7	184.3
Recourse And Non-Recourse Debt And Capital Lease Obligations	522.8	397.4
Deferred Gain on Sale of Property		0.0
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	0.0	0.0
Due to Affiliate	1,871.8	1,750.8
Other Liabilities	54.2	56.8
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,378.9	2,562.0
Liabilities and Equity	4,999.7	4,959.9
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Cash and Cash Equivalents, at Carrying Value	0.1	4.1
Accounts Receivable, after Allowance for Credit Loss	185.7	181.8
Income Taxes Receivable	0.0	0.0
Inventory, Net	398.8	485.8
Property, Plant and Equipment, Net	1,320.7	1,436.3
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	3,136.2	2,925.0
Restricted Cash and Cash Equivalents	0.0	0.0
Goodwill and Other Assets	394.4	198.0
Assets	5,435.9	5,231.0
Accounts Payable	109.1	134.0
Accrued Liabilities	23.2	55.4
Recourse And Non-Recourse Debt And Capital Lease Obligations	0.0	0.0
Deferred Gain on Sale of Property		16.5
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	844.6	781.7
Due to Affiliate	0.0	(0.1)
Other Liabilities	40.9	0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	4,418.1	4,243.5
Liabilities and Equity	5,435.9	5,231.0
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Cash and Cash Equivalents, at Carrying Value	36.3	59.1
Accounts Receivable, after Allowance for Credit Loss	74.0	82.3
Income Taxes Receivable	0.1	0.0
Inventory, Net	34.7	40.9
Property, Plant and Equipment, Net	6,595.8	5,579.7
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	347.0	651.0
Restricted Cash and Cash Equivalents	86.1	132.9
Goodwill and Other Assets	58.6	98.1
Assets	7,232.6	6,644.0
Accounts Payable	90.6	69.9
Accrued Liabilities	152.9	128.7
Recourse And Non-Recourse Debt And Capital Lease Obligations	4,359.1	3,631.8
Deferred Gain on Sale of Property		1.2
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	(8.2)	0.0
Due to Affiliate	0.0	0.0
Other Liabilities	1.2	0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,637.0	2,812.4
Liabilities and Equity	$ 7,232.6	$ 6,644.0