Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	$ 583,287	$ 646,048
Gross Unrealized Gains	44,361	40,573
Gross Unrealized Losses	(299)	(1,379)
Fair Value	627,349	685,242
States and political subdivisions [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	400,687	441,273
Gross Unrealized Gains	31,387	29,026
Gross Unrealized Losses	(106)	(360)
Fair Value	431,968	469,939
Corporate bonds [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	82,824	92,682
Gross Unrealized Gains	1,565	1,539
Gross Unrealized Losses	(12)	(130)
Fair Value	84,377	94,091
Commercial mortgage-backed securities [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	51,529	51,550
Gross Unrealized Gains	6,433	4,195
Fair Value	57,962	55,745
U.S. agency-based mortgage-backed securities [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	32,984	46,096
Gross Unrealized Gains	3,063	4,162
Gross Unrealized Losses	(5)	(44)
Fair Value	36,042	50,214
U.S. Treasury securities and obligations of U.S. Government agencies [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	11,034	9,141
Gross Unrealized Gains	1,721	1,634
Fair Value	12,755	10,775
Asset-backed securities [Member]
Gross unrealized gains and losses and the cost or amortized cost and fair value of investments classified as held-to-maturity
Cost or Amortized Cost/Fixed-maturity securities-held to maturity, at amortized cost	4,229	5,306
Gross Unrealized Gains	192	17
Gross Unrealized Losses	(176)	(845)
Fair Value	$ 4,245	$ 4,478

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 5

-Chapter 3

-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 17

-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 10

-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 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (c)

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 9

-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 7: 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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 8

-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 11

-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 AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 4

-Chapter 3

-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 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 7

-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 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.6)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References+ Details