Schedule 1 Summary of Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 6,901,993
Amount shown in Balance Sheet	7,164,906
Available For Sale Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	6,352,737
Fair Value	6,610,368
Amount shown in Balance Sheet	6,610,368
US Government Agencies Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	70,279
Fair Value	70,969
Amount shown in Balance Sheet	70,969
US States and Political Subdivisions Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	896,130
Fair Value	954,708
Amount shown in Balance Sheet	954,708
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,246,707
Fair Value	2,389,012
Amount shown in Balance Sheet	2,389,012
Corporate Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,251,625
Fair Value	1,276,835
Amount shown in Balance Sheet	1,276,835
Residential Mortgage Backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	805,458
Fair Value	821,694
Amount shown in Balance Sheet	821,694
Commercial Mortgage Backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	593,956
Fair Value	611,631
Amount shown in Balance Sheet	611,631
Asset-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	369,103
Fair Value	366,827
Amount shown in Balance Sheet	366,827
Foreign Government Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	119,479
Fair Value	118,692
Amount shown in Balance Sheet	118,692
Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	291,070
Fair Value	296,352
Amount shown in Balance Sheet	296,352
Banks, Trust and Insurance, Equities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	46,538
Fair Value	46,183
Amount shown in Balance Sheet	46,183
Industrial, Miscellaneous, and All Others [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	244,532
Fair Value	250,169
Amount shown in Balance Sheet	250,169
Short Term Investments Schedule One [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	258,186
Amount shown in Balance Sheet	$ 258,186

This element represents the carrying (reported) amount of the entity's investments as of the balance sheet date. This amount may represent the individual investment's or group of similar investments' original cost, fair value, or such other amount at which the investment is shown in the entity's balance sheet.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 15

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 7

-Subparagraph (SX 210.12-15)

-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611379-123010

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