Summary of discontinued operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of discontinued operations
Rental and other property revenues discontinued operations	$ 5,612	$ 34,922	$ 43,010
Total revenue discontinued operations	5,612	34,922	43,010
Property operating expenses discontinued operations	2,350	16,480	22,645
Depreciation discontinued operations	751	5,563	7,676
General and administrative discontinued operations	515	950	975
Provision on impairment of notes receivable and real estate assets discontinued operations			2,400
Total operating expenses discontinued operations	3,616	22,993	33,696
Other income (expense) discontinued operations	(508)	44	7
Mortgage and loan interest discontinued operations	(1,743)	(8,082)	(12,677)
Deferred borrowing costs amortization discontinued operations	(1,461)	(3,015)	(1,794)
Loan charges and prepayment penalties discontinued operations	(1,656)	(3,245)	(3,471)
Earnings from unconsolidated subsidiaries and investees discontinued operations	1	30	55
Litigation settlement discontinued operations	(250)	(250)	(250)
Total other expenses discontinued operations	(5,617)	(14,518)	(18,130)
Loss from discontinued operations before gain on sale of real estate and taxes.	(3,621)	(2,589)	(8,816)
Gain on sale of real estate from discontinued operations.	61,879	97,405	5,217
Income tax benefit (expense) discontinued operations	(20,390)	(33,186)	1,260
Income (loss) from discontinued operations.	$ 37,868	$ 61,630	$ (2,339)