Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	$ 2,816,250	$ 2,682,142
Equity securities available for sale, fair value	37,184	36,689
Securities, Fair Value	2,853,434	2,718,831
Percent of total	100.00%	100.00%
Priced from external pricing services [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	2,723,705	2,606,714
Equity securities available for sale, fair value	9,402	9,660
Priced from independent broker quotations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	47,546	31,669
Equity securities available for sale, fair value
Priced from internal matrices and calculations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	44,999	43,759
Equity securities available for sale, fair value	27,782	27,029
Level 1 [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	28,623	24,097
Equity securities available for sale, fair value	2,131	2,216
Securities, Fair Value	30,754	26,313
Percent of total	1.00%	1.00%
Level 1 [Member] \| Priced from external pricing services [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	28,623	24,097
Equity securities available for sale, fair value	2,131	2,216
Level 1 [Member] \| Priced from independent broker quotations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Equity securities available for sale, fair value
Level 2 [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	2,742,628	2,614,286
Equity securities available for sale, fair value	33,904	33,350
Securities, Fair Value	2,776,532	2,647,636
Percent of total	97.00%	97.00%
Level 2 [Member] \| Priced from external pricing services [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	2,695,082	2,582,617
Equity securities available for sale, fair value	7,271	7,444
Level 2 [Member] \| Priced from independent broker quotations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	47,546	31,669
Equity securities available for sale, fair value
Level 2 [Member] \| Priced from internal matrices and calculations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Equity securities available for sale, fair value	26,633	25,906
Level 3 [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	44,999	43,759
Equity securities available for sale, fair value	1,149	1,123
Securities, Fair Value	46,148	44,882
Percent of total	2.00%	2.00%
Level 3 [Member] \| Priced from independent broker quotations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Equity securities available for sale, fair value
Level 3 [Member] \| Priced from internal matrices and calculations [Member]
Schedule of Fair Value of Fixed Maturities and Equity Securities
Fixed maturity securities available for sale, carrying value	44,999	43,759
Equity securities available for sale, fair value	$ 1,149	$ 1,123

Amount of debt securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 137

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 320

-Section 50

-Paragraph 2

-Subparagraph (b)-(g)

-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Amount of equity securities categorized neither as held-to-maturity nor as trading.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 3

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 86-40

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 320

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 19

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details