Retirement Benefit Plans - Assets Measured at Fair Value (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	$ 387.1	$ 752.5
Level 1, 2 and 3 | Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	149.1	257.2
Level 1, 2 and 3 | Fair Value, Recurring | Cash and cash equivalents
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	22.9	13.8
Level 1, 2 and 3 | Fair Value, Recurring | Government and agency securities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	11.6	25.4
Level 1, 2 and 3 | Fair Value, Recurring | Corporate bonds - investment grade
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	31.5	82.7
Level 1, 2 and 3 | Fair Value, Recurring | Equity securities - U.S. companies
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.1	0.0
Level 1, 2 and 3 | Fair Value, Recurring | Common collective funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	29.9	42.5
Level 1, 2 and 3 | Fair Value, Recurring | Mutual funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	31.6	51.8
Level 1, 2 and 3 | Fair Value, Recurring | Mutual funds - international equity
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	21.5	41.0
Level 1 | Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	116.7	171.8
Level 1 | Fair Value, Recurring | Cash and cash equivalents
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	22.9	13.8
Level 1 | Fair Value, Recurring | Government and agency securities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	10.7	22.7
Level 1 | Fair Value, Recurring | Corporate bonds - investment grade
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 1 | Fair Value, Recurring | Equity securities - U.S. companies
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.1	0.0
Level 1 | Fair Value, Recurring | Common collective funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	29.9	42.5
Level 1 | Fair Value, Recurring | Mutual funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	31.6	51.8
Level 1 | Fair Value, Recurring | Mutual funds - international equity
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	21.5	41.0
Level 2 | Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	32.4	85.4
Level 2 | Fair Value, Recurring | Cash and cash equivalents
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 2 | Fair Value, Recurring | Government and agency securities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.9	2.7
Level 2 | Fair Value, Recurring | Corporate bonds - investment grade
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	31.5	82.7
Level 2 | Fair Value, Recurring | Equity securities - U.S. companies
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 2 | Fair Value, Recurring | Common collective funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 2 | Fair Value, Recurring | Mutual funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 2 | Fair Value, Recurring | Mutual funds - international equity
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Cash and cash equivalents
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Government and agency securities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Corporate bonds - investment grade
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Equity securities - U.S. companies
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Common collective funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Mutual funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Level 3 | Fair Value, Recurring | Mutual funds - international equity
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.0	0.0
Fair Value Measured at Net Asset Value Per Share | Common collective funds - fixed income
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	82.6	216.6
Fair Value Measured at Net Asset Value Per Share | Equity securities - international companies
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	0.4	0.3
Fair Value Measured at Net Asset Value Per Share | Common collective funds - domestic equities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	19.9	45.9
Fair Value Measured at Net Asset Value Per Share | Common collective funds - international equities
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	17.5	33.6
Fair Value Measured at Net Asset Value Per Share | Common collective funds - diversified growth
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	12.1	18.5
Fair Value Measured at Net Asset Value Per Share | Limited partnerships
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	6.8	10.4
Fair Value Measured at Net Asset Value Per Share | Real estate partnerships
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	5.2	6.6
Fair Value Measured at Net Asset Value Per Share | Other liability-driven investments
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	68.6	138.1
Fair Value Measured at Net Asset Value Per Share | Other assets
Assets, Fair Value Disclosure [Abstract]
Fair value of plan assets at end of year	$ 24.9	$ 25.3