Transactions with related parties (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Transactions with related parties
Gross written premiums	$ 817.6	$ 622.3
Receivables due from affiliates	31.0		$ 16.1
Payables due to affiliates	0.9		$ 0.9
Insurance and MGU affiliates, or their subsidiaries
Transactions with related parties
Gross written premiums	$ 41.3	$ 24.1

Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

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