Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Rockpoint Transaction) (Narrative) (Details)

v3.8.0.1
Recent Transactions (Rockpoint Transaction) (Narrative) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 10, 2017
Feb. 27, 2017
Dec. 31, 2017
Dec. 31, 2016
Preferred Units [Line Items]        
Assets     $ 1,139,322 $ 2,024,522
Mortgages and loans payable     689,412 1,350,973
Other liabilities     80,746 247,212
RRLP [Member]        
Preferred Units [Line Items]        
Assets     1,900,000 1,300,000
Mortgages and loans payable     769,700 480,700
Other liabilities     95,900 $ 40,100
Investment Agreement [Member] | Rockpoint [Member]        
Preferred Units [Line Items]        
Incremental closing payments, Limited Partnership interest $ 150,000      
Investment Agreement [Member] | Rockpoint [Member] | Minimum [Member]        
Preferred Units [Line Items]        
Incremental closing payments, Limited Partnership interest     $ 10,000  
Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]        
Preferred Units [Line Items]        
Contributed amount to obtain equity units   $ 300,000