Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative change related to the adoption of ASU 2016-13	Cumulative effect, period of adoption, adjusted balance	Common Stock Including Additional Paid in Capital [Member]	Common Stock Including Additional Paid in Capital [Member] Cumulative change related to the adoption of ASU 2016-13	Common Stock Including Additional Paid in Capital [Member] Cumulative effect, period of adoption, adjusted balance	Retained earnings	Retained earnings Cumulative change related to the adoption of ASU 2016-13	Retained earnings Cumulative effect, period of adoption, adjusted balance	Accumulated other comprehensive loss	Accumulated other comprehensive loss Cumulative change related to the adoption of ASU 2016-13	Accumulated other comprehensive loss Cumulative effect, period of adoption, adjusted balance
Equity, beginning balance at Dec. 31, 2022	$ 3,073.8			$ 2,478.2			$ 1,072.7			$ (477.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	123.3			0.0			123.3			0.0
Other comprehensive income (loss), net of tax expense	$ 18.1			0.0			0.0			18.1
Stock repurchased and retired (in shares)	55,428
Non-vested common shares issued (in shares)	670,911
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	36,823
Common stock transactions:
Common shares purchased and retired	$ (1.8)			(1.8)			0.0			0.0
Non-vested common shares issued	0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock-based compensation expense	$ 5.0			5.0			0.0			0.0
Common dividends (in dollars per share)	$ 0.94
Common cash dividend declared	$ (97.2)			0.0			(97.2)			0.0
Equity, ending balance at Jun. 30, 2023	3,121.2			2,481.4			1,098.8			(459.0)
Equity, beginning balance at Mar. 31, 2023	3,160.3			2,478.7			1,080.7			(399.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	67.0			0.0			67.0			0.0
Other comprehensive income (loss), net of tax expense	$ (59.9)			0.0			0.0			(59.9)
Stock repurchased and retired (in shares)	348
Non-vested common shares issued (in shares)	660,048
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	21,035
Common stock transactions:
Common shares purchased and retired	$ 0.0			0.0			0.0			0.0
Non-vested common shares issued	0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock-based compensation expense	$ 2.7			2.7			0.0			0.0
Common dividends (in dollars per share)	$ 0.47
Common cash dividend declared	$ (48.9)			0.0			(48.9)			0.0
Equity, ending balance at Jun. 30, 2023	3,121.2			2,481.4			1,098.8			(459.0)
Equity, beginning balance at Dec. 31, 2023	3,227.5	$ 1.2	$ 3,228.7	2,448.9	$ 0.0	$ 2,448.9	1,135.1	$ 1.2	$ 1,136.3	(356.5)	$ 0.0	$ (356.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	118.4			0.0			118.4			0.0
Other comprehensive income (loss), net of tax expense	$ (29.0)			0.0			0.0			(29.0)
Stock repurchased and retired (in shares)	45,448
Non-vested common shares issued (in shares)	738,098
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	73,658
Common stock transactions:
Common shares purchased and retired	$ (1.1)			(1.1)			0.0			0.0
Non-vested common shares issued	0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock-based compensation expense	$ 6.1			6.1			0.0			0.0
Common dividends (in dollars per share)	$ 0.94
Common cash dividend declared	$ (97.8)			0.0			(97.8)			0.0
Equity, ending balance at Jun. 30, 2024	3,225.3			2,453.9			1,156.9			(385.5)
Equity, beginning balance at Mar. 31, 2024	3,209.7			2,450.7			1,145.9			(386.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60.0			0.0			60.0			0.0
Other comprehensive income (loss), net of tax expense	$ 1.4			0.0			0.0			1.4
Stock repurchased and retired (in shares)	1,758
Non-vested common shares issued (in shares)	52,735
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	61,982
Common stock transactions:
Common shares purchased and retired	$ 0.0			0.0			0.0			0.0
Non-vested common shares issued	0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock-based compensation expense	$ 3.2			3.2			0.0			0.0
Common dividends (in dollars per share)	$ 0.47
Common cash dividend declared	$ (49.0)			0.0			(49.0)			0.0
Equity, ending balance at Jun. 30, 2024	$ 3,225.3			$ 2,453.9			$ 1,156.9			$ (385.5)