Summary of Significant Accounting Policies (Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Assets with foreclosure elections	$ 113,100
Operating loss carryforwards		$ 582,400
Total income tax (expense) benefit	(815)	948	$ 10,166
Provision adjustment			2,800
Taxable REIT Subsidiaries
Entity Information [Line Items]
Operating loss carryforwards	25,600	21,300
Assets owned taxable subsidiaries	538,000
Current tax benefit (expense)	(447)	531	9,751
Total income tax (expense) benefit	(447)	531	9,751
Income (loss) of subsidiaries	25,900	33,100	49,400
Deferred tax assets	78,107	63,258
Valuation allowance	(78,107)	(63,258)
Net deferred tax assets (liabilities)	0	0
Real estate asset basis differences	35,300	26,100
Other credits	2,300
Deferred expenses and other items	14,900	15,900
REIT
Entity Information [Line Items]
Current tax benefit (expense)	(500)	400
Income taxes paid	$ 2,000	$ 6,000	$ 200