Schedule VI - Supplemental Information Concerning Property-Casualty Insurance Operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Deferred policy acquisition costs	$ 39,343	$ 37,792	$ 34,426
Reserves for losses and settlement expenses	661,309	610,181	583,097
Discount, if any, deducted from reserves	0	0	0
Unearned premiums	232,093	220,627	196,215
Earned premiums	540,722	515,506	458,846
Net investment income	46,477	43,032	44,155
Losses and settlement expenses incurred related to current year	406,266	346,072	329,121
Losses and settlement expenses incurred related to prior years	(20,792)	(12,785)	(25,733)
Amortization of deferred policy acquisition costs	99,042	94,728	84,275
Paid losses and settlement expenses	330,087	305,266	308,137
Premiums written	$ 552,610	$ 534,077	$ 478,481

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Amount of amortization expense on deferred policy acquisition cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 3

-Subparagraph (SX 210.12-18)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 18

-Article 12

+ Details

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- Definition

Amount of expense for claims incurred in the current reporting period and related claims settlement costs.

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Amount of deferred policy acquisition cost related to property-casualty insurance policy written.

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- Definition

The amount of discount that may be deducted from the reserve for unpaid claims and claims adjustment expense.

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Amount of property-casualty insurance premium revenue earned on insurance policies.

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Amount of net investment income earned by property-casualty insurance underwriter.

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- Definition

Payments of claims and claims adjustment expenses during the period of a property-casualty insurance entity.

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Amount of actual premium written by property-casualty insurance underwriter.

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Amount of expense for claims incurred in prior reporting periods and related claims settlement costs.

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The amount of reserve, policy claim payable and loss expense incurred by property-casualty insurance underwriter.

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Amount of property-casualty insurance premium revenue not yet earned on insurance policies.

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