Consolidated Statements of Stockholders' Equity (USD $)
In Thousands, except Share data, unless otherwise specified
Total
Common Stock
Capital in Excess of Par Value
Accumulated Distributions in Excess of Earnings
Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2008 $ 1,614,976 $ 2,023 $ 1,763,432 $ (121,929) $ (28,550)
Beginning balance, shares at Dec. 31, 2008   202,296,748      
Issuance of common stock, shares   7,473,804      
Issuance of common stock 71,063 75 70,988    
Distributions to investors (133,957)     (133,957)  
Other offering costs (563)   (563)    
Redemptions of common stock, shares   (5,107,932)      
Redemptions of common stock (48,303) (51) (48,252)    
Stock compensation expense 13   13    
Changes in redeemable common stock (22,714)   (22,714)    
Comprehensive income:          
Net income 22,406     22,406  
Unrealized gain/loss on marketable securities 19,072       19,072
Unrealized gain (loss) on interest rate swaps (9)       (9)
Total comprehensive income 41,469        
Ending balance at Dec. 31, 2009 1,521,984 2,047 1,762,904 (233,480) (9,487)
Ending balance, shares at Dec. 31, 2009   204,662,620      
Issuance of common stock, shares   7,037,054      
Issuance of common stock 61,377 70 61,307    
Distributions to investors (129,497)     (129,497)  
Other offering costs (9)   (9)    
Redemptions of common stock, shares   (2,382,328)      
Redemptions of common stock (21,638) (24) (21,614)    
Stock compensation expense 7   7    
Changes in redeemable common stock 75,523   75,523    
Comprehensive income:          
Net income 30,430     30,430  
Unrealized gain/loss on marketable securities 23,051       23,051
Unrealized gain (loss) on interest rate swaps (853)       (853)
Total comprehensive income 52,628        
Ending balance at Dec. 31, 2010 1,560,375 2,093 1,878,118 (332,547) 12,711
Ending balance, shares at Dec. 31, 2010 209,317,346 209,317,346      
Issuance of common stock, shares   6,986,717      
Issuance of common stock 59,696 70 59,626    
Distributions to investors (131,063)     (131,063)  
Redemptions of common stock, shares   (6,152,371)      
Redemptions of common stock (52,590) (62) (52,528)    
Changes in redeemable common stock (2,245)   (2,245)    
Comprehensive income:          
Net income 53,809     53,809  
Unrealized gain/loss on marketable securities (1,713)       (1,713)
Reclassification of previous unrealized gain on marketable securities into net income (14,654)       (14,654)
Unrealized gain (loss) on interest rate swaps 98       98
Total comprehensive income 37,540        
Ending balance at Dec. 31, 2011 $ 1,471,713 $ 2,101 $ 1,882,971 $ (409,801) $ (3,558)
Ending balance, shares at Dec. 31, 2011 210,151,692 210,151,692