Common and Preferred Shares (Details Textual) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Nov. 15, 2021	Sep. 15, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 23, 2019
Class of Stock [Line Items]
Common share repurchases authorized (up to) (in shares)						120,000,000
Common shares repurchased (in shares)			46,000,000	7,000,000	40,000,000
Common shares remaining under share repurchase authorizations (in shares)			56,000,000
Shares held as treasury shares (in shares)			2,500,000	2,500,000	2,600,000
Cost basis of treasury stock			$ 271.0	$ 279.0	$ 292.0
Preferred shares, authorized (in shares)			20,000,000	20,000,000
Preferred shares, par value (in dollars per share)			$ 1.667	$ 1.667
Liquidation price per share (in dollars per share)			1,000,000
Depositary shares redemption amount			$ 1,000
Equity adjustments in connection with redemption of Preferred Shares			$ 16.0	$ 0.0	$ 0.0
Warrants, issued and outstanding (in shares)			0	0	0
Repurchase Agreements
Share Repurchase Commissions [Line Items]
Cost basis of common stock repurchased			$ 7,600.0	$ 900.0	$ 4,600.0
Commissions paid included in cost basis of common stock repurchased			$ 5.6	$ 1.0	$ 6.2
Series D Preferred Stock
Class of Stock [Line Items]
Preferred shares, par value (in dollars per share)			$ 1.667
Fixed dividend rate per annum (as a percent)			3.55%
Series C Preferred Stock
Class of Stock [Line Items]
Payments for redemption of preferred stock		$ 850.0
Fixed dividend rate per annum (as a percent)		4.90%
Series B Preferred Stock
Class of Stock [Line Items]
Payments for redemption of preferred stock	$ 750.0
Fixed dividend rate per annum (as a percent)	5.20%