Mergers with Real Estate Businesses - Fair Value of Assets Acquired and Liabilities Assumed at Cole Acquisition (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 07, 2014
Identifiable liabilities assumed at fair value:
Goodwill	$ 1,462,203	$ 1,656,374	$ 1,894,794
Cole Real Estate Investments, Inc. [Member]
Identifiable assets acquired at fair value:
Land				$ 1,737,839
Buildings, fixtures and improvements				5,901,827
Acquired intangible lease assets				1,324,217
Total real estate investments				8,963,883
Investment in unconsolidated entities				103,966
Investment securities, at fair value				151,197
Loans held for investment, net				72,326
Cash and cash equivalents				149,965
Restricted cash				15,704
Intangible assets				305,000
Deferred costs and other assets				94,667
Due from affiliates				3,301
Total identifiable assets purchased				9,860,009
Identifiable liabilities assumed at fair value:
Mortgage notes payable				2,706,585
Credit facilities				1,309,000
Other debt				49,013
Below-market lease liabilities				212,433
Accounts payable and accrued expenses				142,243
Deferred rent, derivative and other liabilities				204,558
Dividends payable				6,271
Due to affiliates				44,242
Total liabilities assumed				4,674,345
Non-controlling interests				24,766
Net identifiable assets acquired				5,160,898
Goodwill				2,262,547
Net assets acquired				$ 7,423,445