| **Debt (Details) (USD $)In Thousands, unless otherwise specified**                                                                                                                                                             | Sep. 30, 2013 | Dec. 31, 2012 | Dec. 31, 2007 |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|---------------|
| **Debt Instrument [Line Items]**                                                                                                                                                                                               |          |          |          |
| Long term debt                                                                                                                                                                                                                 | $ 37,832      | $ 36,062      |          |
| In-substance defeased debt, interest payable monthly at 5.62% at September 30, 2013 and December 31, 2012, secured and paid by pledged treasury securities, due October 1, 2015                                                |          |          |          |
| **Debt Instrument [Line Items]**                                                                                                                                                                                               |          |          |          |
| Long term debt                                                                                                                                                                                                                 | 26,404        | 26,818        | 29,300        |
| Community Development District debt, secured by certain real estate and standby note purchase agreements, due May 1, 2016 — May 1, 2039, bearing interest at 6.70% to 7.15% at September 30, 2013 and December 31, 2012 |          |          |          |
| **Debt Instrument [Line Items]**                                                                                                                                                                                               |          |          |          |
| Long term debt                                                                                                                                                                                                                 | $ 11,428      | $ 9,244       |          |

| X                                                                                                                                                           |
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| - Definition
Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.
+ References
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