Mortgage Notes Payable - Schedule of Long-term Debt Instruments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) property	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Deferred financing costs	$ (5,719)	$ (7,446)
Mortgage notes payable	$ 502,808	524,262
Mortgage notes payable
Debt Instrument [Line Items]
Encumbered Properties | property	73
Outstanding Loan Amount	$ 508,527	531,708
Effective Interest Rate	3.00%
Deferred financing costs	$ (5,719)	(7,446)
Mortgage notes payable	$ 502,808	524,262
Mortgage notes payable | Quest Diagnostics | LIBOR
Debt Instrument [Line Items]
Interest rate spread	2.00%
Mortgage notes payable | EUR
Debt Instrument [Line Items]
Encumbered Properties | property	12
Outstanding Loan Amount	$ 186,931	181,858
Mortgage notes payable | EUR | Finnair
Debt Instrument [Line Items]
Encumbered Properties | property	4
Outstanding Loan Amount	$ 31,840	30,976
Effective Interest Rate	2.20%
Mortgage notes payable | EUR | Tokmanni
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 32,485	31,603
Effective Interest Rate	2.40%
Mortgage notes payable | EUR | Rheinmetall
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 11,884	11,561
Effective Interest Rate	2.60%
Mortgage notes payable | EUR | OBI DIY
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 5,045	4,908
Effective Interest Rate	2.40%
Mortgage notes payable | EUR | RWE AG
Debt Instrument [Line Items]
Encumbered Properties | property	3
Outstanding Loan Amount	$ 70,070	68,169
Effective Interest Rate	1.60%
Mortgage notes payable | EUR | Rexam
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 5,897	5,737
Effective Interest Rate	1.80%
Mortgage notes payable | EUR | Metro Tonic
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 29,710	28,904
Effective Interest Rate	1.70%
Mortgage notes payable | GBP
Debt Instrument [Line Items]
Encumbered Properties | property	40
Outstanding Loan Amount	$ 195,769	223,461
Mortgage notes payable | GBP | McDonald's
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 986	1,125
Effective Interest Rate	4.10%
Mortgage notes payable | GBP | Wickes Building Supplies I
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 2,525	2,882
Effective Interest Rate	3.70%
Mortgage notes payable | GBP | Everything Everywhere
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 5,188	5,922
Effective Interest Rate	4.00%
Mortgage notes payable | GBP | Thames Water
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 7,782	8,882
Effective Interest Rate	4.10%
Mortgage notes payable | GBP | Wickes Building Supplies II
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 2,140	2,443
Effective Interest Rate	4.20%
Mortgage notes payable | GBP | Northern Rock
Debt Instrument [Line Items]
Encumbered Properties | property	2
Outstanding Loan Amount	$ 6,809	7,772
Effective Interest Rate	4.50%
Mortgage notes payable | GBP | Wickes Building Supplies III
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 2,464	2,813
Effective Interest Rate	4.40%
Mortgage notes payable | GBP | Provident Financial
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 16,537	18,875
Effective Interest Rate	4.10%
Mortgage notes payable | GBP | Crown Crest
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 24,968	28,498
Effective Interest Rate	4.30%
Mortgage notes payable | GBP | Aviva
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 20,363	23,242
Effective Interest Rate	3.80%
Mortgage notes payable | GBP | Bradford & Bingley
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 9,806	11,192
Effective Interest Rate	3.50%
Mortgage notes payable | GBP | Intier Automotive Interiors
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 6,128	6,995
Effective Interest Rate	3.50%
Mortgage notes payable | GBP | Capgemini
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 7,134	8,142
Effective Interest Rate	3.20%
Mortgage notes payable | GBP | Fujitisu
Debt Instrument [Line Items]
Encumbered Properties | property	3
Outstanding Loan Amount	$ 32,129	36,684
Effective Interest Rate	3.20%
Mortgage notes payable | GBP | Amcor Packaging
Debt Instrument [Line Items]
Encumbered Properties | property	7
Outstanding Loan Amount	$ 4,055	4,628
Effective Interest Rate	3.60%
Mortgage notes payable | GBP | Fife Council
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 2,378	2,715
Effective Interest Rate	3.60%
Mortgage notes payable | GBP | Malthrust
Debt Instrument [Line Items]
Encumbered Properties | property	3
Outstanding Loan Amount	$ 4,150	4,737
Effective Interest Rate	3.60%
Mortgage notes payable | GBP | Talk Talk
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 4,961	5,663
Effective Interest Rate	3.60%
Mortgage notes payable | GBP | HBOS
Debt Instrument [Line Items]
Encumbered Properties | property	3
Outstanding Loan Amount	$ 6,991	7,979
Effective Interest Rate	3.60%
Mortgage notes payable | GBP | DFS Trading
Debt Instrument [Line Items]
Encumbered Properties | property	5
Outstanding Loan Amount	$ 13,151	15,010
Effective Interest Rate	3.40%
Mortgage notes payable | GBP | DFS Trading
Debt Instrument [Line Items]
Encumbered Properties | property	2
Outstanding Loan Amount	$ 3,079	3,514
Effective Interest Rate	3.40%
Mortgage notes payable | GBP | HP Enterprise Services
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 12,045	13,748
Effective Interest Rate	3.40%
Mortgage notes payable | USD
Debt Instrument [Line Items]
Encumbered Properties | property	21
Outstanding Loan Amount	$ 125,827	126,389
Mortgage notes payable | USD | Quest Diagnostics
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 52,800	52,800
Effective Interest Rate	2.50%
Mortgage notes payable | USD | Western Digital
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 17,759	17,982
Effective Interest Rate	5.30%
Mortgage notes payable | USD | AT&T Services
Debt Instrument [Line Items]
Encumbered Properties | property	1
Outstanding Loan Amount	$ 33,550	33,550
Effective Interest Rate	2.50%
Mortgage notes payable | USD | AT&T Services | Adjusted LIBOR
Debt Instrument [Line Items]
Interest rate spread	2.00%
Mortgage notes payable | USD | Encanto Restaurants
Debt Instrument [Line Items]
Encumbered Properties | property	18
Outstanding Loan Amount	$ 21,718	$ 22,057
Effective Interest Rate	6.30%