Reserves for Unpaid Losses and Loss Adjustment Expenses Multi-line Quota Share Reinsurance (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Reinsurance Retention Policy [Line Items]
Commutations of MLQS	$ 0	$ 27,929
Multi Line Quota Share Treaty - 2015 [Member]
Reinsurance Retention Policy [Line Items]
Commutations of MLQS		$ 27,900

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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