Debt - Schedule of Weighted Average Interest Rates (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument
Interest expense	$ 10.3	$ 7.8	$ 32.5	$ 21.2
Specialty Insurance Distribution (NSM)
Debt Instrument
Weighted Average			276.6	273.6
Interest expense			$ 17.3	$ 16.1
Weighted Average Interest rate	8.30%	7.80%	8.30%	7.80%
Specialty Insurance Distribution (NSM) | Term loan - hedged
Debt Instrument
Weighted Average			$ 147.1	$ 148.5
Interest expense			$ 10.0	$ 10.0
Weighted Average Interest rate	9.10%	9.00%	9.10%	9.00%
Specialty Insurance Distribution (NSM) | Term loan - unhedged
Debt Instrument
Weighted Average			$ 129.5	$ 125.1
Interest expense			$ 7.3	$ 6.1
Weighted Average Interest rate	7.50%	6.50%	7.50%	6.50%