Note 14. Earnings Per Common Share Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number of Shares Outstanding, Basic and Diluted									5.5	5.8	6.4
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									0.2	0.0	0.0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 22.3	$ 48.1	$ 37.6	$ 31.2	$ 28.0	$ 28.5	$ 37.3	$ 15.2	$ 139.2	$ 109.0	$ 610.2
Net Income (Loss) Attributable to Noncontrolling Interest	0.1	1.3	(0.4)	0.5	(0.4)	(0.6)	(1.4)	(1.4)	1.5	(3.8)	(11.1)
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic									(1.8)	(2.2)	(13.5)
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities									0.0	0.0	0.3
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic									138.9	103.0	585.9
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (0.8)	$ (0.4)	$ (0.8)	$ (1.1)	$ (0.3)	$ (0.2)	$ 28.2	$ 26.4	(3.1)	54.1	103.4
Undistributed Discontinued Operation Earnings (Loss), Allocation to Participating Securities, Basic									0.0	(0.6)	(1.9)
Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic									(3.1)	53.5	101.5
Net Income (Loss) Available to Common Stockholders, Basic									$ 135.8	$ 156.5	$ 687.4
Weighted Average Number of Shares Outstanding, Basic									125.6	144.0	148.6
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements									1.7	1.0	0.5
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities, Treasury Stock Method									0.0	1.4	2.9
Weighted Average Number of Shares Outstanding, Diluted									127.3	146.4	152.0
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.18	$ 0.39	$ 0.29	$ 0.24	$ 0.20	$ 0.19	$ 0.24	$ 0.09	$ 1.11	$ 0.72	$ 3.94
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0	(0.01)	(0.01)	0	0	0.19	0.18	(0.02)	0.37	0.68
Earnings Per Share, Basic	0.17	0.39	0.28	0.23	0.20	0.19	0.43	0.27	1.09	1.09	4.62
Income (Loss) from Continuing Operations, Per Diluted Share	0.18	0.39	0.29	0.24	0.19	0.19	0.24	0.09	1.09	0.70	3.85
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	(0.01)	0	(0.01)	(0.01)	0	0	0.19	0.17	(0.02)	0.37	0.67
Earnings Per Share, Diluted	$ 0.17	$ 0.39	$ 0.28	$ 0.23	$ 0.19	$ 0.19	$ 0.43	$ 0.26	$ 1.07	$ 1.07	$ 4.52