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BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	12 Months Ended			3 Months Ended		9 Months Ended
	Dec. 31, 2014 subsidiary Investment	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2014
Variable Interest Entity [Line Items]
Negative fund performance that would cause reversal of performance fees	$ 15,800,000
Accrued performance fees	8,500,000	17,500,000	8,600,000	8,500,000		8,500,000
Number of wholly-owned subsidiaries managing KWE	1kw_NumberofSubsidiaries
Performance fee percentage	20.00%kw_PerformanceFeePercentFee
Number of investments in joint ventures classified as investment companies	3			3		3
Fair value option, number of investments	3kw_FairValueOptionNumberofInvestments			3kw_FairValueOptionNumberofInvestments		3kw_FairValueOptionNumberofInvestments
Operating distributions from joint ventures	88,800,000		40,400,000
Net cash provided by operating activities	98,100,000	31,300,000	16,700,000
Investing distributions from joint ventures	111,800,000		38,700,000
Net cash used in investing activities	(2,473,200,000)	(348,800,000)	(399,700,000)
Percentage of investments in foreign platforms	45.00%			45.00%		45.00%
Goodwill, Impairment Loss	0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss
Kennedy Wilson Europe Real Estate, Pllc [Member]
Variable Interest Entity [Line Items]
Proceeds from initial public offering					1,700,000,000
Cash investment as part of initial public offering					145,200,000
Assets contributed as part of initial public offering					58,300,000
Additional shares acquired (in shares)				4,645,169		3,100,000
Purchase of additional shares	51,100,000			75,000,000		51,100,000
Ownership percentage by parent	14.90%			14.90%		14.90%
Property management fee percentage	1.00%
Management fee payable	14,000,000			14,000,000		14,000,000
Annual return percentage	10.00%
Performance fee payable vesting period	3 years
Percentage of Investment Hedged	46.00%			46.00%		46.00%
Scenario, Previously Reported [Member]
Variable Interest Entity [Line Items]
Operating distributions from joint ventures			30,400,000
Net cash provided by operating activities			6,800,000
Investing distributions from joint ventures			48,700,000
Net cash used in investing activities			(389,700,000)
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable interest entity, number of investments	1
Loans Payable [Member] \| Performance Guarantee [Member]
Variable Interest Entity [Line Items]
Guarantees, maximum exposure	$ 54,900,000			$ 54,900,000		$ 54,900,000
Minimum [Member]
Variable Interest Entity [Line Items]
Percentage of Investment Hedged	50.00%			50.00%		50.00%
Maximum [Member]
Variable Interest Entity [Line Items]
Percentage of Investment Hedged	100.00%			100.00%		100.00%