Gain on Sales of Real Estate (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) property	Sep. 30, 2017 USD ($) property	Sep. 30, 2018 USD ($) property	Sep. 30, 2017 USD ($) property
Gain (Loss) on Sale of Investments [Abstract]
Properties sold \| property	20	17	60	46
Proceeds from sales of real estate	$ 35,500	$ 25,500	$ 83,024	$ 69,486
Gain on sales of properties	$ 7,800	$ 4,300	$ 18,800	$ 17,700

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228

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