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