Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Operating losses	$ 69.7	$ 62.3
Interest expense carryforward	183.3	153.5
Bad debts	6.5	5.1
Accrued expenses	12.9	9.5
Capital loss and credit carryforwards	13.6	15.4
Pension and postretirement benefits	28.5	33.9
Foreign exchange	1.9	9.0
ASC 842 - Lease liability	10.2	16.0
Equity Compensation	11.6	10.5
Other	5.4	9.3
Total deferred tax assets	343.6	324.5
Valuation allowance	(39.2)	(37.0)
Net deferred tax assets	304.4	287.5
Deferred tax liabilities:
Intangibles	(1,109.0)	(1,230.8)
Commission Assets	(39.2)	(35.6)
Fixed assets	(14.7)	(12.5)
ASC 842 - ROU asset	(9.8)	(15.1)
Other	(1.8)	(1.2)
Total deferred tax liabilities	(1,174.5)	(1,295.2)
Net deferred tax (liabilities) assets	$ (870.1)	$ (1,007.7)