Common Share Data (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Numerator for basic and diluted earnings per share - income (loss) available to common stockholders		$ (604.8)	$ 412.2
Denominator for basic earnings per share - weighted-average shares (a)	[1]	300,280,398	299,020,956
Effect of dilutive securities - stock based compensation awards		0	1,151,897
Denominator for diluted earnings per shares adjusted weighted average shares and assumed conversions (a) (in shares)	[1]	300,280,398	300,172,853
Net income (loss) per share: Basic (in dollars per share)		$ (2.01)	$ 1.38
Net income (loss) per share: Diluted (in dollars per share)		$ (2.01)	$ 1.37
Stock based compensation awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from earnings per share computations		9,620,404	3,284,700

[1] (a) In calculating earnings per share, pertinent accounting rules require that common shares owned by the Company's Employee Savings and Stock Ownership Plan that are not yet allocated to participants in the plan be excluded from the calculation. Such shares are issued and outstanding, and have the same voting and other rights applicable to all common shares.