Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts receivable	$ 690	$ 715
Allowance for doubtful notes receivable	$ 0	$ 7,083
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	96,376,827	95,470,903
Common stock, shares outstanding (in shares)	96,376,827	95,470,903
Series A Preferred Stock [Member]
Preferred stock, shares issued (in shares)	1,657,206	1,657,206
Preferred stock, shares outstanding (in shares)	1,657,206	1,657,206
Series D Preferred Stock [Member]
Preferred stock, shares issued (in shares)	9,468,706	9,468,706
Preferred stock, shares outstanding (in shares)	9,468,706	9,468,706
Series E Preferred Stock [Member]
Preferred stock, shares issued (in shares)	0	4,630,000
Preferred stock, shares outstanding (in shares)	0	4,630,000
Series F Preferred Stock [Member]
Preferred stock, shares issued (in shares)	4,800,000	0
Preferred stock, shares outstanding (in shares)	4,800,000	0
Series G Preferred Stock [Member]
Preferred stock, shares issued (in shares)	6,200,000	0
Preferred stock, shares outstanding (in shares)	6,200,000	0