Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Available-for-sale securities measured at fair value
Cash and cash equivalents	$ 279,327	$ 230,214
Total available-for-sale securities	45,061	44,829
Total	324,388	275,043
Long-term debt	43,470
Equity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	9,944	8,876
Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	35,117	35,953
U.S. Treasury and U.S. government agencies [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	1,758	1,447
Corporate bonds [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	11,117	10,860
Commercial mortgage-backed securities [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	10,741	11,644
State, municipalities, and political subdivisions [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	10,664	11,066
Redeemable preferred stock [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	837	936
(Level 1) [Member]
Available-for-sale securities measured at fair value
Cash and cash equivalents	279,327	230,214
Total available-for-sale securities	33,144	32,321
Total	312,471	262,535
Long-term debt	43,470
(Level 1) [Member] \| Equity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	9,944	8,876
(Level 1) [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	23,200	23,445
(Level 1) [Member] \| U.S. Treasury and U.S. government agencies [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	582	583
(Level 1) [Member] \| Corporate bonds [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	11,117	10,860
(Level 1) [Member] \| State, municipalities, and political subdivisions [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	10,664	11,066
(Level 1) [Member] \| Redeemable preferred stock [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	837	936
(Level 2) [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	11,917	12,508
Total	11,917	12,508
(Level 2) [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	11,917	12,508
(Level 2) [Member] \| U.S. Treasury and U.S. government agencies [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	1,176	864
(Level 2) [Member] \| Commercial mortgage-backed securities [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities	10,741	11,644
(Level 3) [Member]
Available-for-sale securities measured at fair value
Cash and cash equivalents
Total available-for-sale securities
Total
Long-term debt
(Level 3) [Member] \| Equity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| U.S. Treasury and U.S. government agencies [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| Corporate bonds [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| Commercial mortgage-backed securities [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| State, municipalities, and political subdivisions [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities
(Level 3) [Member] \| Redeemable preferred stock [Member] \| Fixed-maturity securities [Member]
Available-for-sale securities measured at fair value
Total available-for-sale securities

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.

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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 includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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