Equity Investments in the Managed Programs and Real Estate - Equity Method Investments Excluding the Managed Programs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments in Programs
Equity investments in real estate	$ 298,893	$ 275,473
CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	3.456%	3.087%
Equity investments in real estate	$ 99,584	$ 87,912
Real Estate Investments
Investments in Programs
Equity investments in real estate	$ 138,076	141,991
Real Estate Investments | The New York Times Company | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	45.00%
Equity investments in real estate	$ 69,668	70,976
Real Estate Investments | Frontier Spinning Mills, Inc. | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	40.00%
Equity investments in real estate	$ 24,138	24,288
Real Estate Investments | Beach House JV, LLC | Third Party
Investments in Programs
Equity investments in real estate	$ 15,105	15,318
Real Estate Investments | Actebis Peacock GmbH | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	30.00%
Equity investments in real estate	$ 11,205	12,186
Real Estate Investments | Waldaschaff Automotive GmbH and Wagon Automotive Nagold GmbH | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	33.00%
Equity investments in real estate	$ 8,887	9,507
Real Estate Investments | C1000 Logestiek Vastgoed B.V. | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	15.00%
Equity investments in real estate	$ 8,739	9,381
Real Estate Investments | Wanbishi Archives Co. Ltd. | CPA: 17 - Global
Investments in Programs
Equity method investment, ownership percentage	3.00%
Equity investments in real estate	$ 334	$ 335