Transactions with related parties (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Transactions with related parties
Gross written premiums	$ 622.3	$ 615.2
Receivables due from affiliates	19.4		$ 14.3
Payables due to affiliates	0.7
Insurance and MGU affiliates, or their subsidiaries
Transactions with related parties
Gross written premiums	$ 24.1	$ 19.3

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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