Earnings per Common Share Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income	$ 226.0	$ 257.5	$ 202.2
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Weighted average common shares outstanding for basic earnings per share computation	102,978,301	103,752,206	103,274,070
Dilutive effect of stock-based compensation (in shares)	212,563	27,897	66,929
Weighted average common shares outstanding for diluted earnings per common share computation	103,190,864	103,780,103	103,340,999
Restricted Stock [Member]
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	71,728	119,144	52,027
Performance Shares
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	809,865	908,476	470,622