Guarantor and Non-Guarantor Financial Statements (Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 63.7	$ (1.3)	$ 113.6	$ (3.9)
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	23.1	(3.7)	21.9	(18.0)
Amounts reclassified out of AOCI during the period	(8.3)	0	(7.1)	0
Unrealized forward contract, foreign currency (loss) gain	(2.1)	2.2	(3.6)	5.8
Total other comprehensive gain (loss) for the period	12.7	(1.5)	11.2	(12.2)
Comprehensive income (loss)	76.4	(2.8)	124.8	(16.1)
Comprehensive (income) loss attributable to noncontrolling interests	(44.1)	0.9	(81.5)	1.9
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	32.3	(1.9)	43.3	(14.2)
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	63.6	(1.4)	113.6	(3.9)
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	23.1	(3.7)		(18.0)
Amounts reclassified out of AOCI during the period	(8.3)
Unrealized forward contract, foreign currency (loss) gain	(2.1)	2.2		5.8
Total other comprehensive gain (loss) for the period	12.7	(1.5)	11.2	(12.2)
Comprehensive income (loss)	76.3	(2.9)	124.8	(16.1)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	76.3	(2.9)	124.8	(16.1)
Kennedy-Wilson, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	65.3	0.7	116.9	(0.2)
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	23.1	(3.7)	21.9	(18.0)
Amounts reclassified out of AOCI during the period	(8.3)		(7.1)
Unrealized forward contract, foreign currency (loss) gain	(2.1)	2.2	(3.6)	5.8
Total other comprehensive gain (loss) for the period	12.7	(1.5)	11.2	(12.2)
Comprehensive income (loss)	78.0	(0.8)	128.1	(12.4)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	78.0	(0.8)	128.1	(12.4)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	127.7	20.2	209.6	34.6
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	29.1	(5.1)	23.9	(18.0)
Amounts reclassified out of AOCI during the period	(8.3)		(8.3)
Unrealized forward contract, foreign currency (loss) gain	(3.6)	2.0	(1.2)	5.2
Total other comprehensive gain (loss) for the period	17.2	(3.1)	14.4	(12.8)
Comprehensive income (loss)	144.9	17.1	224.0	21.8
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	144.9	17.1	224.0	21.8
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	75.8	0.8	153.0	9.6
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	(3.1)	(0.5)	(3.9)	(2.5)
Amounts reclassified out of AOCI during the period	0		1.2
Unrealized forward contract, foreign currency (loss) gain	(1.2)	0	(1.2)	0
Total other comprehensive gain (loss) for the period	(4.3)	(0.5)	(3.9)	(2.5)
Comprehensive income (loss)	71.5	0.3	149.1	7.1
Comprehensive (income) loss attributable to noncontrolling interests	(44.1)	0.9		1.9
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	27.4	1.2	67.6	9.0
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(268.7)	(21.6)	(479.5)	(44.0)
Other comprehensive income (loss), net of tax:
Unrealized foreign currency translation gain (loss)	(49.1)	9.3	(41.9)	38.5
Amounts reclassified out of AOCI during the period	16.6		14.2
Unrealized forward contract, foreign currency (loss) gain	6.9	(4.2)	6.0	(11.0)
Total other comprehensive gain (loss) for the period	(25.6)	5.1	(21.7)	27.5
Comprehensive income (loss)	(294.3)	(16.5)	(501.2)	(16.5)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.	$ (294.3)	$ (16.5)	$ (501.2)	$ (16.5)