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Name:	us-gaap_ReinsuranceRetentionPolicyLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reserves for Unpaid Losses and Loss Adjustment Expenses Multi-line Quota Share Reinsurance (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jan. 01, 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