Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Recent Transactions (Rockpoint Transaction) (Narrative) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 10, 2017
Feb. 27, 2017
Dec. 31, 2018
Dec. 31, 2017
Preferred Units [Line Items]        
Assets     $ 1,115,458 $ 1,139,322
Mortgages and loans payable     686,797 689,412
Other liabilities     67,072 80,746
RRLP [Member]        
Preferred Units [Line Items]        
Assets     2,300,000 1,900,000
Mortgages and loans payable     1,100,000 769,700
Other liabilities     57,000 $ 95,900
Investment Agreement [Member] | Rockpoint [Member]        
Preferred Units [Line Items]        
Incremental closing payments, Limited Partnership interest $ 150,000   105,000  
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