Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Impairment Charges from Continuing Operations
Impairment charges	$ 0	$ 2,019	$ (70)
Level 3 | Nonrecurring
Impairment Charges from Continuing Operations
Impairment charges	3,778	2,019	(70)
Level 3 | Nonrecurring | Operating expenses
Impairment Charges from Continuing Operations
Impairment charges	0	2,019	(70)
Direct financing lease | Level 3 | Nonrecurring
Impairment Charges from Continuing Operations
Fair value measurement	0	0	0
Impairment charges	0	0	(70)
CMBS | Level 3 | Nonrecurring
Impairment Charges from Continuing Operations
Fair value measurement	0	0	0
Impairment charges	0	2,019	0
Equity method investments | Level 3 | Nonrecurring
Impairment Charges from Continuing Operations
Fair value measurement	23,278	0	0
Impairment charges	$ 3,778	$ 0	$ 0