CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
CONSOLIDATED BALANCE SHEETS
Mortgage loans receivable, allowance for doubtful accounts (in dollars)	$ 401	$ 782
Straight-line rent receivable, allowance for doubtful accounts (in dollars)	1,567	1,557
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares issued	2,000,000	2,000,000
Preferred stock, shares outstanding	2,000,000	2,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	30,713,000	30,544,000
Common stock, shares outstanding	30,713,000	30,544,000
Straight-line rent receivable from a lessee that qualifies as a related party (in dollars)	$ 3,203	$ 3,191