Real Estate Transactions (Acquisitions) (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) tract
Real Estate [Line Items]
Number of tracts of land acquired	3
Value of land acquired \| $	$ 68.4
Midtown Atlanta, Georgia
Real Estate [Line Items]
Number of tracts of land acquired	2
Tempe, Arizona
Real Estate [Line Items]
Number of tracts of land acquired	1

Payments to develop real estate assets is the process of adding improvements on or to a parcel of land. Such improvements may include drainage, utilities, subdividing, access, buildings, and any combination of these elements; and are generally classified as cash flow from investing activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

Name:	us-gaap_PaymentsToDevelopRealEstateAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration