Fair Value Measurements (Details 2) (Fair Value, Measurements, Nonrecurring, Level 3, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Impairment Disclosure
Impairment charges on properties	$ 4,225	$ 7,970	$ 7,026	$ 18,056
Continuing Operations
Impairment Disclosure
Impairment charges on properties	4,225	6,554	7,026	12,082
Continuing Operations | Real Estate
Impairment Disclosure
Total fair value measurements	6,665	0	6,665	0
Impairment charges on properties	3,472	0	5,538	0
Continuing Operations | Net investments in direct financing leases
Impairment Disclosure
Total fair value measurements	3,157	0	3,157	0
Impairment charges on properties	753	0	753	0
Continuing Operations | Equity investments in real estate
Impairment Disclosure
Total fair value measurements	0	4,350	0	4,350
Impairment charges on properties	0	6,554	735	12,082
Discontinued Operations
Impairment Disclosure
Impairment charges on properties	0	1,416	0	5,974
Discontinued Operations | Real Estate
Impairment Disclosure
Total fair value measurements	0	9,468	0	16,376
Impairment charges on properties	0	1,416	0	4,903
Discontinued Operations | Operating real estate
Impairment Disclosure
Total fair value measurements			0	3,709
Impairment charges on properties			$ 0	$ 1,071