Guarantor and Non-Guarantor Financial Statements - Consolidating Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Total revenue	$ 132.2	$ 124.7
Total income from unconsolidated subsidiaries	5.7	105.4
Gain on sale of real estate, net	19.2	1.9
Total expenses	124.5	139.1
Income from consolidated subsidiaries	0.0	0.0
Interest expense	(62.3)	(50.5)
Gain on early extinguishment of debt	0.1	0.0
Other income (loss)	(3.0)	5.8
(Loss) income before benefit from (provision for) income taxes	(32.6)	48.2
Benefit from (provision for) income taxes	3.9	(8.2)
Net (loss) income	(28.7)	40.0
Net (income) loss attributable to the noncontrolling interests	(4.2)	0.1
Preferred dividends	(7.9)	(5.3)
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	(40.8)	34.8
Rental
Condensed Financial Statements, Captions [Line Items]
Total revenue	106.6	104.2
Hotel
Condensed Financial Statements, Captions [Line Items]
Total revenue	10.6	6.5
Investment Management Fees
Condensed Financial Statements, Captions [Line Items]
Total revenue	11.0	11.3
Loan and other
Condensed Financial Statements, Captions [Line Items]
Total revenue	3.7	2.3
Reportable Legal Entities | Parent
Condensed Financial Statements, Captions [Line Items]
Total revenue	0.0	0.0
Total income from unconsolidated subsidiaries	0.0	0.0
Gain on sale of real estate, net	0.0	0.0
Total expenses	7.6	7.1
Income from consolidated subsidiaries	(21.2)	47.1
Interest expense	0.0	0.0
Gain on early extinguishment of debt	0.0
Other income (loss)	0.1	0.0
(Loss) income before benefit from (provision for) income taxes	(28.7)	40.0
Benefit from (provision for) income taxes	0.0	0.0
Net (loss) income	(28.7)	40.0
Net (income) loss attributable to the noncontrolling interests	0.0	0.0
Preferred dividends	(7.9)	(5.3)
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	(36.6)	34.7
Reportable Legal Entities | Kennedy-Wilson, Inc.
Condensed Financial Statements, Captions [Line Items]
Total revenue	0.1	0.0
Total income from unconsolidated subsidiaries	0.0	2.0
Gain on sale of real estate, net	0.0	0.0
Total expenses	17.0	22.5
Income from consolidated subsidiaries	17.3	92.8
Interest expense	(25.2)	(21.7)
Gain on early extinguishment of debt	0.0
Other income (loss)	(2.1)	2.8
(Loss) income before benefit from (provision for) income taxes	(26.9)	53.4
Benefit from (provision for) income taxes	5.7	(6.3)
Net (loss) income	(21.2)	47.1
Net (income) loss attributable to the noncontrolling interests	0.0	0.0
Preferred dividends	0.0	0.0
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	(21.2)	47.1
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Total revenue	56.4	53.8
Total income from unconsolidated subsidiaries	(26.9)	8.5
Gain on sale of real estate, net	3.7	0.0
Total expenses	44.0	52.8
Income from consolidated subsidiaries	37.5	96.0
Interest expense	(10.8)	(9.7)
Gain on early extinguishment of debt	(0.5)
Other income (loss)	0.9	(0.3)
(Loss) income before benefit from (provision for) income taxes	16.3	95.5
Benefit from (provision for) income taxes	1.0	(2.7)
Net (loss) income	17.3	92.8
Net (income) loss attributable to the noncontrolling interests	0.0	0.0
Preferred dividends	0.0	0.0
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	17.3	92.8
Reportable Legal Entities | Non-guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Total revenue	75.7	70.9
Total income from unconsolidated subsidiaries	32.6	94.9
Gain on sale of real estate, net	15.5	1.9
Total expenses	55.9	56.7
Income from consolidated subsidiaries	0.0	0.0
Interest expense	(26.3)	(19.1)
Gain on early extinguishment of debt	0.6
Other income (loss)	(1.9)	3.3
(Loss) income before benefit from (provision for) income taxes	40.3	95.2
Benefit from (provision for) income taxes	(2.8)	0.8
Net (loss) income	37.5	96.0
Net (income) loss attributable to the noncontrolling interests	(4.2)	0.1
Preferred dividends	0.0	0.0
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	33.3	96.1
Elimination
Condensed Financial Statements, Captions [Line Items]
Total revenue	0.0	0.0
Total income from unconsolidated subsidiaries	0.0	0.0
Gain on sale of real estate, net	0.0	0.0
Total expenses	0.0	0.0
Income from consolidated subsidiaries	(33.6)	(235.9)
Interest expense	0.0	0.0
Gain on early extinguishment of debt	0.0
Other income (loss)	0.0	0.0
(Loss) income before benefit from (provision for) income taxes	(33.6)	(235.9)
Benefit from (provision for) income taxes	0.0	0.0
Net (loss) income	(33.6)	(235.9)
Net (income) loss attributable to the noncontrolling interests	0.0	0.0
Preferred dividends	0.0	0.0
Net (loss) income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	$ (33.6)	$ (235.9)