Shareholders' Equity Loss Per Common Share - Common Shares Repurchased (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		25 Months Ended
	Apr. 30, 2022	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2020
Sale of stock
Authorized value of shares for repurchase					$ 500.0
Repurchase and retired common shares		3,300,000	619,749	12,500,000
Repurchase and retired common shares, Value		$ 93.1	$ 19.2	$ 355.6
Average purchase price		$ 27.86	$ 30.96	$ 28.45
Subsequent Event
Sale of stock
Repurchase and retired common shares	707,000
Repurchase and retired common shares, Value	$ 19.4
Average purchase price	$ 27.39