Other Assets and Other Liabilities (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of deferred tax assets and liabilities [Line Items]
Operating loss carryforwards			$ 856,400
Taxable REIT Subsidiaries
Schedule of deferred tax assets and liabilities [Line Items]
Deferred tax assets	$ 53,678	$ 53,910
Valuation allowance	(53,678)	(53,910)
Net deferred tax assets (liabilities)	0	0
Real estate basis differences	36,000	40,000
Deferred expenses differences	16,000	10,700
Operating loss carryforwards	$ 1,700	$ 3,200