Real Estate and In-Place Lease Value - Schedule of Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Real Estate [Abstract]
Pro forma revenues	$ 279.3	$ 181.0	$ 639.4	$ 543.1
Pro forma net income	10.8	17.5	37.7	44.8
Pro forma net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	$ (8.1)	$ 1.6	$ 5.6	$ 1.2
Pro forma net (loss) income per share:
Basic (in dollars per share)	$ (0.07)	$ 0.02	$ 0.05	$ 0.01
Diluted (in dollars per share)	$ (0.07)	$ 0.02	$ 0.05	$ 0.01

Business Acquisition, Pro Forma Net Income (Loss) Available to Common Stockholders

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- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a 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)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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