GUARANTOR AND NON-GUARANTOR FINANCIAL STATEMENTS (Consolidated Statement of Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net (loss) income	$ (20.5)	$ (3.0)	$ 63.7	$ 49.8	$ 20.6	$ (2.7)	$ (1.3)	$ (2.7)	$ 90.1	$ 13.9		$ 6.7
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									(0.2)	0		3.3
Unrealized foreign currency translation (loss) gain									(46.4)	(9.3)		(1.5)
Amounts reclassified from accumulated other comprehensive income									(7.1)	2.8		0
Unrealized gain (loss) on forward currency derivatives									16.3	3.1		5.7
Total other comprehensive (loss) income for the period									(37.4)	(3.4)		7.5
Comprehensive income									52.7	10.5		14.2
Comprehensive income attributable to noncontrolling interests									(15.6)	(20.3)		(2.6)
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									37.1	(9.8)		11.6
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									90.1	13.9		6.9
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									(0.2)			3.3
Unrealized foreign currency translation (loss) gain									(46.4)	(9.3)		(1.5)
Amounts reclassified from accumulated other comprehensive income									(7.1)	2.8
Unrealized gain (loss) on forward currency derivatives									16.3	3.1		5.7
Total other comprehensive (loss) income for the period									(37.4)	(3.4)		7.5
Comprehensive income									52.7	10.5		14.4
Comprehensive income attributable to noncontrolling interests									0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									52.7	10.5		14.4
Kennedy-Wilson, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									106.0	21.7		14.9
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									(0.2)			3.3
Unrealized foreign currency translation (loss) gain									(46.4)	(9.3)		(1.5)
Amounts reclassified from accumulated other comprehensive income									(7.1)	2.8
Unrealized gain (loss) on forward currency derivatives									16.3	3.1		5.7
Total other comprehensive (loss) income for the period									(37.4)	(3.4)		7.5
Comprehensive income									68.6	18.3		22.4
Comprehensive income attributable to noncontrolling interests									0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									68.6	18.3		22.4
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									278.4	105.4		66.3
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation (loss) gain									1.9	(10.0)	[1]	(2.2)
Amounts reclassified from accumulated other comprehensive income									1.2	2.8
Unrealized gain (loss) on forward currency derivatives									4.9	5.0	[1]	6.4
Total other comprehensive (loss) income for the period									8.0	(2.2)	[1]	4.2
Comprehensive income									286.4	103.2	[1]	70.5
Comprehensive income attributable to noncontrolling interests									0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									286.4	103.2	[1]	70.5
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									215.5	51.3		38.3
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation (loss) gain									(41.0)	0.8		(0.3)
Amounts reclassified from accumulated other comprehensive income									(8.3)	0
Unrealized gain (loss) on forward currency derivatives									15.2
Total other comprehensive (loss) income for the period									(34.1)	0.8		(0.3)
Comprehensive income									181.4	52.1		38.0
Comprehensive income attributable to noncontrolling interests									(15.6)	(20.3)		(2.6)
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									165.8	31.8		35.4
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(599.9)	(178.4)		(119.7)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									0.2			(3.3)
Unrealized foreign currency translation (loss) gain									85.5	18.5		4.0
Amounts reclassified from accumulated other comprehensive income									14.2	(5.6)
Unrealized gain (loss) on forward currency derivatives									(36.4)	(8.1)		(12.1)
Total other comprehensive (loss) income for the period									63.5	4.8		(11.4)
Comprehensive income									(536.4)	(173.6)		(131.1)
Comprehensive income attributable to noncontrolling interests									0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									(536.4)	(173.6)		(131.1)
Consolidated Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									90.1	13.9		6.7
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									(0.2)			3.3
Unrealized foreign currency translation (loss) gain									(46.4)	(9.3)		(1.5)
Amounts reclassified from accumulated other comprehensive income									(7.1)	2.8
Unrealized gain (loss) on forward currency derivatives									16.3	3.1		5.7
Total other comprehensive (loss) income for the period									(37.4)	(3.4)		7.5
Comprehensive income									52.7	10.5		14.2
Comprehensive income attributable to noncontrolling interests									(15.6)	(20.3)		(2.6)
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									$ 37.1	$ (9.8)		$ 11.6

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