Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Equity [Abstract]
Common shares, shares authorized (in shares)	100,000,000		100,000,000
Preferred stock, shares authorized (in shares)	50,000,000		50,000,000
Cash dividends declared per common share (in usd per share)	$ 0.05	$ 0.31
Dividend declared	$ 2.7	$ 16.7
Total authorizations which remain available for use	$ 110.0
Common shares acquired (in shares)	0	0
Deferred tax (benefit) expense included in OCI	$ (8.3)	$ (11.0)