RECENT ACQUISITIONS (Narrative) (Details) $ in Millions	6 Months Ended
Jun. 30, 2015 USD ($)
Business Combinations [Abstract]
Business combination and acquisition cost expensed	$ 4.1
Total revenues recognized from business combination	1.7
Operating expense recognized from business combination	$ 0.7

Business Combination, Pro Forma Information, Operating Expense of Acquiree since Acquisition Date, Actual

No definition available.

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Namespace Prefix:	kbsriii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- References

No definition available.

+ Details

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