Insurance Operations - Gross Written Premiums (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($) item	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($) item	Dec. 31, 2018
Insurance Operations
Percentage of direct premiums sourced from distribution party acquired by a third party insurance carrier					13.50%
Number of distribution partners contributing the largest amounts of direct written premiums | item	3	3	3	3
Direct premiums written by the largest distribution partners | $	$ 75.4	$ 52.0	$ 208.4	$ 183.9