Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Legal Fees
Related Party Transaction
Amounts of Transactions		$ 708
Spouse of Executive Officer | Legal Fees
Related Party Transaction
Amounts of Transactions		354
Related party interest in billings (percentage)			50.00%
Director | AmRisc gross written premiums
Related Party Transaction
Amounts of Transactions	$ 107,619	94,005
Related party interest in billings (percentage)	7.70%
Director | AmRisc Fees and Commission
Related Party Transaction
Amounts of Transactions	$ 28,979	25,599
Director | AmRisc ceded premiums written
Related Party Transaction
Amounts of Transactions	1,545	$ 1,561
Director | AmRisc Rent
Related Party Transaction
Amounts of Transactions	5
Director | AmRisc net premiums receivable
Related Party Transaction
Amounts of Transactions	$ 44,759