Reinsurance - Effects of Reinsurance on Premiums Written and Earned (Details) $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($)
Written
Direct premiums	$ 539,499
Ceded premiums	(539,489)
Net premiums	10
Earned
Direct premiums	493,854
Ceded premiums	(493,844)
Net premiums	$ 10

Amount of earned premiums ceded to other entities.

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Amount of written premiums ceded to other entities.

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