CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Notes and interest receivable	$ 140,327	$ 127,865
Allowance for doubtful accounts	14,269	15,770
Deferred revenue from sales to related parties	33,904	77,332
Accounts payable and other liabilities to related parties	$ 25,576	$ 39,373
Series A Preferred stock, par value (in dollars per share)	$ 2.00	$ 2.00
Series A Preferred stock, authorized (in shares)	15,000,000	15,000,000
Series A Preferred stock, issued (in shares)	614	2,000,614
Series A Preferred stock, outstanding (in shares)	614	2,000,614
Series A Preferred stock, liquidation preference (in dollars per share)	$ 10	$ 10
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	16,412,861	15,997,076
Common stock, outstanding (in shares)	15,930,145	15,514,360
Shares held by subsidiaries (in shares)	2,000,614	1,800,614
Treasury stock (in shares)	415,785	415,785
Convertible Preferred Stock [Member]
Shares held by subsidiaries (in shares)	1,800,000	900,000
Related Party [Member]
Notes and interest receivable	$ 105,803	$ 99,410
Allowance for doubtful accounts	14,269	14,269
Deferred revenue from sales to related parties	37,416	56,887
Accounts payable and other liabilities to related parties	$ 107	$ 11,893
Southern Properties Capital LTD [Member] | Common Stock [Member]
Shares held by subsidiaries (in shares)	140,000	140,000
Treasury stock (in shares)	140,000	140,000