Series A Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 18, 2019	Mar. 17, 2017	Dec. 04, 2015
Class of Stock [Line Items]
Series A preferred shares, shares issued	400,000	900,000
Deemed Dividend on Preferred Stock Redemption	$ 67.0		$ (58.0)
Deemed dividend on modification of Series A convertible preferred stock			4.0
Financial instruments subject to redemption, settlement terms, maximum number of shares	13,300,000	29,000,000.0
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Series A preferred shares, shares issued						820,000
Aggregate purchase price						$ 820.0
Stated Value Of Preferred Shares Per Share	$ 1,000
Direct Issuance Expenses						$ 26.0
Dividends, Preferred Stock, Paid-in-kind	$ 43.0	$ 46.0	45.0
Accrued Dividends	$ 1.0	$ 3.0
Secondary offering by the preferred shareholders					342,000
Redeemed Shares of Preferred Stock				512,221	90,000
Repurchase price per share of common stock upon conversion					$ 48.47
Dividend Rate for preferred shares						5.50%
Conversion price per preferred share						$ 30.00
Conversion rate per preferred share	33.333
Blackstone Shares Converted into Common Shares				237,673
Cash Paid for the Redemption of Preferred Stock				$ 302.0
Stock Issued During Period, Shares, Conversion of Convertible Securities	9,160,000
Retained Earnings [Member]
Class of Stock [Line Items]
Deemed Dividend on Preferred Stock Redemption	$ (67.0)		(58.0)
Deemed dividend on modification of Series A convertible preferred stock			$ 4.0