Real Estate Investments (Property Dispositions and Held for Sale Assets) (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) property	Mar. 31, 2015 USD ($) property	Dec. 31, 2015 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds after debt assumptions and closing costs	$ 176,137	$ 245,548
Gain related to sale, including goodwill	17,175	(31,368)
Foreclosed upon property net book value	14,500,266		$ 15,006,124
Gain related to sale of unconsolidated entities	10,404	28
Goodwill allocated to dispositions	$ 13,516	$ 23,680
2016 Property Dispositions [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property	58
Aggregate proceeds	$ 193,700
Company's share of proceeds	102,100
Proceeds after debt assumptions and closing costs	133,800
Debt assumption	55,000
Gain related to sale, including goodwill	18,800
Goodwill included in sale	$ 11,300
Number of properties owned by consolidated joint ventures disposed of | property	1
Net proceeds	$ 113,500
Proceeds from Real Estate and Real Estate Joint Ventures	42,300
Debt repayments	57,000
Gain related to sale of unconsolidated entities	$ 10,200
Number of properties classified held for sale | property	19
Net loss on sale of properties	$ 1,700
Goodwill allocated to dispositions	2,200
Red Lobster [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Company's share of proceeds	$ 193,100
2015 Property Dispositions [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties disposed | property		11
Aggregate proceeds		$ 271,800
Proceeds after debt assumptions and closing costs		245,500
Gain related to sale, including goodwill		31,400
Goodwill included in sale		$ 23,700
Number of properties classified held for sale | property			17
Foreclosed Upon Real Estate Property [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties foreclosed upon | property		1
Foreclosed upon property net book value		$ 38,200