Guarantor and Non-Guarantor Financial Statements (Income Statements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	$ 39.0	$ 19.5	$ 19.5	$ 52.1	$ 33.1
Rental and hotel	42.6	10.3	10.3	67.8	16.8
Sale of real estate	6.1	6.1	6.1	17.4	8.5
Loans and other	4.3	0.5	0.5	6.0	0.9
Total revenue	92.0	36.4	36.4	143.3	59.3
Operating expenses
Commission and marketing	0.9	1.3	1.3	1.8	1.8
Rental and hotel operating	17.9	4.6	4.6	32.1	7.7
Cost of real estate sold	3.9	5.1	5.1	13.5	7.0
Compensation and related	32.2	18.3	18.3	52.8	31.9
General and administrative	8.4	6.4	6.4	16.5	11.8
Depreciation and amortization	25.3	4.4	4.4	32.6	7.5
Total operating expenses	88.6	40.1	40.1	149.3	67.7
Income from unconsolidated investments	31.0	14.8	14.8	33.8	16.9
(Loss) income from consolidated subsidiaries	0		0	0	0
Operating income	34.4	11.1	11.1	27.8	8.5
Non-operating income (expense)
Acquisition-related gains	86.0	0	(0.5)	170.3	9.5
Acquisition-related expenses	(7.6)	(0.5)		(11.6)	(0.5)
Interest expense-investment	(11.1)	(2.8)	(2.8)	(16.4)	(4.6)
Interest expense-corporate	(14.7)	(9.7)	(9.7)	(25.2)	(19.4)
Other income	2.1	0.1	0.1	2.9	0.4
Income (loss) before (provision for) benefit from income taxes	89.1	(1.8)	(1.8)	147.8	(6.1)
(Provision for) benefit from income taxes	(25.4)	0.5	0.5	(34.2)	2.2
Net income (loss)	63.7	(1.3)		113.6	(3.9)
Net income attributable to the noncontrolling interests	(25.3)	0.9	0.9	(62.7)	1.9
Net loss attributable to Kennedy-Wilson Holdings, Inc.	38.4			50.9
Preferred dividends and accretion of preferred stock issuance costs	(2.1)	(2.1)	(2.1)	(4.1)	(4.1)
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	36.3	(2.5)	(2.5)	46.8	(6.1)
Parent [Member]
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	0		0	0	0
Rental and hotel	0		0	0	0
Sale of real estate	0		0	0	0
Loans and other	0		0	0	0
Total revenue	0		0	0	0
Operating expenses
Commission and marketing	0		0	0	0
Rental and hotel operating	0		0	0	0
Cost of real estate sold	0		0	0	0
Compensation and related	1.7		1.7	3.4	3.4
General and administrative	0		0.3	0	0.3
Depreciation and amortization	0		0	0	0
Total operating expenses	1.7		2.0	3.4	3.7
Income from unconsolidated investments	0		0	0	0
(Loss) income from consolidated subsidiaries	65.3		0.6	117.0	(0.2)
Operating income	63.6		(1.4)	113.6	(3.9)
Non-operating income (expense)
Acquisition-related gains	0		0	0	0
Acquisition-related expenses	0			0	0
Interest expense-investment	0		0	0	0
Interest expense-corporate	0		0	0	0
Other income	0		0	0	0
Income (loss) before (provision for) benefit from income taxes	63.6		(1.4)	113.6	(3.9)
(Provision for) benefit from income taxes	0		0	0	0
Net income (loss)	63.6	(1.4)		113.6	(3.9)
Net income attributable to the noncontrolling interests	0		0	0	0
Net loss attributable to Kennedy-Wilson Holdings, Inc.	63.6			113.6
Preferred dividends and accretion of preferred stock issuance costs	(2.1)		(2.1)	(4.1)	(4.1)
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	61.5		(3.5)	109.5	(8.0)
Kennedy-Wilson, Inc. [Member]
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	0.4		0.4	0.5	0.5
Rental and hotel	0		0	0	0
Sale of real estate	0		0	0	0
Loans and other	0		0	0.1	0
Total revenue	0.4		0.4	0.6	0.5
Operating expenses
Commission and marketing	0		0.3	0	0.4
Rental and hotel operating	0		0	0	0
Cost of real estate sold	0		0	0	0
Compensation and related	20.2		8.6	30.2	13.6
General and administrative	2.7		2.3	5.6	4.4
Depreciation and amortization	0.2		0.1	0.5	0.3
Total operating expenses	23.1		11.3	36.3	18.7
Income from unconsolidated investments	1.2		0	1.2	0
(Loss) income from consolidated subsidiaries	127.6		20.3	209.5	34.7
Operating income	106.1		9.4	175.0	16.5
Non-operating income (expense)
Acquisition-related gains	(7.0)		0	(7.0)	0
Acquisition-related expenses	0			0	0
Interest expense-investment	0		0	0	0
Interest expense-corporate	(14.7)		(9.7)	(25.2)	(19.4)
Other income	(1.8)		0.2	0.2	0.2
Income (loss) before (provision for) benefit from income taxes	82.6		(0.1)	143.0	(2.7)
(Provision for) benefit from income taxes	(17.3)		0.8	(26.1)	2.5
Net income (loss)	65.3	0.7		116.9	(0.2)
Net income attributable to the noncontrolling interests	0		0	0	0
Net loss attributable to Kennedy-Wilson Holdings, Inc.	65.3			116.9
Preferred dividends and accretion of preferred stock issuance costs	0		0	0	0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	65.3		0.7	116.9	(0.2)
Guarantor Subsidiaries [Member]
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	35.4		7.3	48.5	14.2
Rental and hotel	3.0		1.5	6.4	3.2
Sale of real estate	0		6.1	0.6	8.5
Loans and other	3.8		0.5	4.3	0.9
Total revenue	42.2		15.4	59.8	26.8
Operating expenses
Commission and marketing	0.6		1.0	1.4	1.4
Rental and hotel operating	0.9		0.8	2.4	1.7
Cost of real estate sold	0		5.1	0.7	7.0
Compensation and related	8.8		3.4	16.3	7.0
General and administrative	0		0.7	4.0	2.1
Depreciation and amortization	2.6		1.2	4.8	2.3
Total operating expenses	12.9		12.2	29.6	21.5
Income from unconsolidated investments	29.2		16.7	30.9	20.2
(Loss) income from consolidated subsidiaries	75.8		0.7	153.0	9.5
Operating income	134.3		20.6	214.1	35.0
Non-operating income (expense)
Acquisition-related gains	0		(0.2)	3.7	0
Acquisition-related expenses	(1.2)			(1.6)	(0.2)
Interest expense-investment	0		(0.2)	0	(0.5)
Interest expense-corporate	0		0	0	0
Other income	2.7		0	1.5	0.3
Income (loss) before (provision for) benefit from income taxes	135.8		20.2	217.7	34.6
(Provision for) benefit from income taxes	(8.1)		0	(8.1)	0
Net income (loss)	127.7	20.2		209.6	34.6
Net income attributable to the noncontrolling interests	0		0	0	0
Net loss attributable to Kennedy-Wilson Holdings, Inc.	127.7			209.6
Preferred dividends and accretion of preferred stock issuance costs	0		0		0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	127.7		20.2	209.6	34.6
Non-Guarantor Subsidiaries [Member]
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	3.2		11.8	3.1	18.4
Rental and hotel	39.6		8.8	61.4	13.6
Sale of real estate	6.1		0	16.8	0
Loans and other	0.5		0	1.6	0
Total revenue	49.4		20.6	82.9	32.0
Operating expenses
Commission and marketing	0.3		0	0.4	0
Rental and hotel operating	17.0		3.8	29.7	6.0
Cost of real estate sold	3.9		0	12.8	0
Compensation and related	1.5		4.6	2.9	7.9
General and administrative	5.7		3.1	6.9	5.0
Depreciation and amortization	22.5		3.1	27.3	4.9
Total operating expenses	50.9		14.6	80.0	23.8
Income from unconsolidated investments	0.6		(2.0)	1.7	(3.3)
(Loss) income from consolidated subsidiaries	0		0	0	0
Operating income	(0.9)		4.0	4.6	4.9
Non-operating income (expense)
Acquisition-related gains	93.0		(0.3)	173.6	9.5
Acquisition-related expenses	(6.4)			(10.0)	(0.3)
Interest expense-investment	(11.1)		(2.6)	(16.4)	(4.2)
Interest expense-corporate	0		0	0	0
Other income	1.2		0	1.2	0
Income (loss) before (provision for) benefit from income taxes	75.8		1.1	153.0	9.9
(Provision for) benefit from income taxes	0		(0.3)	0	(0.3)
Net income (loss)	75.8	0.8		153.0	9.6
Net income attributable to the noncontrolling interests	(25.3)		0.9	(62.7)	1.9
Net loss attributable to Kennedy-Wilson Holdings, Inc.	50.5			90.3
Preferred dividends and accretion of preferred stock issuance costs	0		0		0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	50.5		1.7	90.3	11.5
Eliminations [Member]
Revenue
Investment management, property services and research fees (includes $7.3 and $8.3 of related party fees)	0		0	0	0
Rental and hotel	0		0	0	0
Sale of real estate	0		0	0	0
Loans and other	0		0	0	0
Total revenue	0		0	0	0
Operating expenses
Commission and marketing	0		0	0	0
Rental and hotel operating	0		0	0	0
Cost of real estate sold	0		0	0	0
Compensation and related	0		0	0	0
General and administrative	0		0	0	0
Depreciation and amortization	0		0	0	0
Total operating expenses	0		0	0	0
Income from unconsolidated investments	0		0.1	0	0
(Loss) income from consolidated subsidiaries	(268.7)		(21.6)	(479.5)	(44.0)
Operating income	(268.7)		(21.5)	(479.5)	(44.0)
Non-operating income (expense)
Acquisition-related gains	0		0	0	0
Acquisition-related expenses	0			0	0
Interest expense-investment	0		0	0	0.1
Interest expense-corporate	0		0	0	0
Other income	0		(0.1)	0	(0.1)
Income (loss) before (provision for) benefit from income taxes	(268.7)		(21.6)	(479.5)	(44.0)
(Provision for) benefit from income taxes	0		0	0	0
Net income (loss)	(268.7)	(21.6)		(479.5)	(44.0)
Net income attributable to the noncontrolling interests	0		0	0	0
Net loss attributable to Kennedy-Wilson Holdings, Inc.	(268.7)			(479.5)
Preferred dividends and accretion of preferred stock issuance costs	0		0	0	0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders	$ (268.7)		$ (21.6)	$ (479.5)	$ (44.0)