Accrued Liabilities and Deferred Credits - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2006 a	Dec. 31, 2014 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred revenue	$ 15,299		$ 15,299			$ 15,309
Liability For Potential Settlement Of Ongoing SEC Investigation	3,500		3,500
Accrued Professional Fees	3,900		3,900
Other Expense, Nonoperating, Cost Of Ongoing SEC Investigation	7,430	$ 0	7,430	$ 0
Florida Department of Transportation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred revenue	$ 12,500		$ 12,500			$ 12,500
Acres of land sold | a					3,900