Guarantor and Non-Guarantor Financial Statements - Consolidating Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue
Total revenue	$ 143.0	$ 185.8	$ 427.4	$ 593.7
Expenses
General and administrative	8.4	11.7	30.2	36.6
Depreciation and amortization	46.4	51.5	141.7	158.7
Total expenses	147.9	177.2	444.8	578.6
Income from unconsolidated investments	84.0	24.0	131.6	60.9
Income from consolidated subsidiaries	0.0	0.0	0.0	0.0
Non-operating income (expense)
Gain on sale of real estate	6.3	39.4	252.4	304.2
Acquisition-related expenses	(4.0)	(0.4)	(5.9)	(0.6)
Interest expense	(51.8)	(55.2)	(162.8)	(181.3)
Other income (loss)	0.0	3.4	(0.6)	14.6
Income before provision for income taxes	29.6	19.8	197.3	212.9
Benefit from (provision for) income taxes	(10.2)	(6.9)	(35.1)	(33.7)
Net income	19.4	12.9	162.2	179.2
Net loss (income) attributable to the noncontrolling interests	1.3	(0.8)	(96.0)	(59.9)
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	20.7	12.1	66.2	119.3
Rental [Member]
Revenue
Total revenue	108.3	123.4	336.1	392.6
Expenses
Cost of goods and services	39.0	38.2	113.3	119.5
Hotel [Member]
Revenue
Total revenue	25.1	43.5	62.9	117.6
Expenses
Cost of goods and services	17.3	30.6	47.6	90.8
Sale of Real Estate [Member]
Revenue
Total revenue	0.0	6.5	1.1	48.7
Expenses
Cost of goods and services	0.0	5.8	1.2	45.6
Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	9.6	12.4	27.3	34.8
Commission and Marketing [Member]
Expenses
Cost of goods and services	1.2	1.1	2.9	4.6
Compensation and Related [Member]
Expenses
Cost of goods and services	35.6	38.3	107.9	122.8
Reportable Legal Entities [Member] \| Parent [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
General and administrative	0.0	0.0	0.0	0.0
Depreciation and amortization	0.0	0.0	0.0	0.0
Total expenses	7.5	9.2	25.1	27.9
Income from unconsolidated investments	0.0	0.0	0.0	0.0
Income from consolidated subsidiaries	26.9	22.1	187.3	207.1
Non-operating income (expense)
Gain on sale of real estate	0.0	0.0	0.0	0.0
Acquisition-related expenses	0.0	0.0	0.0	0.0
Interest expense	0.0	0.0	0.0	0.0
Other income (loss)	0.0	0.0	0.0	0.0
Income before provision for income taxes	19.4	12.9	162.2	179.2
Benefit from (provision for) income taxes		0.0	0.0	0.0
Net income	19.4	12.9	162.2	179.2
Net loss (income) attributable to the noncontrolling interests	0.0	0.0	0.0	0.0
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	19.4	12.9	162.2	179.2
Reportable Legal Entities [Member] \| Parent [Member] \| Rental [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Parent [Member] \| Hotel [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Parent [Member] \| Sale of Real Estate [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Parent [Member] \| Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Parent [Member] \| Commission and Marketing [Member]
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Parent [Member] \| Compensation and Related [Member]
Expenses
Cost of goods and services	7.5	9.2	25.1	27.9
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
General and administrative	4.4	4.3	14.4	13.6
Depreciation and amortization	0.2	0.3	0.9	1.0
Total expenses	22.2	18.5	65.1	62.5
Income from unconsolidated investments	(0.3)	(0.2)	0.1	(0.9)
Income from consolidated subsidiaries	76.2	61.9	336.1	338.5
Non-operating income (expense)
Gain on sale of real estate	0.0	0.0	0.0	0.0
Acquisition-related expenses	(2.7)	0.0	(2.7)	0.0
Interest expense	(16.6)	(18.5)	(53.3)	(57.9)
Other income (loss)	0.5	2.9	1.5	12.9
Income before provision for income taxes	34.9	27.6	216.6	230.1
Benefit from (provision for) income taxes	(8.0)	(5.5)	(29.3)	(23.0)
Net income	26.9	22.1	187.3	207.1
Net loss (income) attributable to the noncontrolling interests	0.0	0.0	0.0	0.0
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	26.9	22.1	187.3	207.1
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Rental [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Hotel [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Sale of Real Estate [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Commission and Marketing [Member]
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Kennedy-Wilson, Inc. [Member] \| Compensation and Related [Member]
Expenses
Cost of goods and services	17.6	13.9	49.8	47.9
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Revenue
Total revenue	52.1	51.0	154.0	160.5
Expenses
General and administrative	3.7	5.2	11.3	15.9
Depreciation and amortization	15.0	13.4	45.0	42.6
Total expenses	45.6	51.0	134.7	153.4
Income from unconsolidated investments	74.5	14.6	70.3	38.2
Income from consolidated subsidiaries	(0.7)	58.3	274.6	271.9
Non-operating income (expense)
Gain on sale of real estate	8.2	0.0	8.2	61.4
Acquisition-related expenses	(0.1)	(0.1)	(0.2)	(0.1)
Interest expense	(12.5)	(11.6)	(36.9)	(40.8)
Other income (loss)	0.0	0.0	0.2	0.1
Income before provision for income taxes	75.9	61.2	335.5	337.8
Benefit from (provision for) income taxes	0.3	0.7	0.6	0.7
Net income	76.2	61.9	336.1	338.5
Net loss (income) attributable to the noncontrolling interests	0.0	0.0	0.0	0.0
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	76.2	61.9	336.1	338.5
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Rental [Member]
Revenue
Total revenue	43.1	39.4	128.4	128.5
Expenses
Cost of goods and services	16.6	17.5	46.7	47.3
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Hotel [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Sale of Real Estate [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	9.0	11.6	25.6	32.0
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Commission and Marketing [Member]
Expenses
Cost of goods and services	1.2	1.1	2.9	4.6
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member] \| Compensation and Related [Member]
Expenses
Cost of goods and services	9.1	13.8	28.8	43.0
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member]
Revenue
Total revenue	90.9	134.8	273.4	433.2
Expenses
General and administrative	0.3	2.2	4.5	7.1
Depreciation and amortization	31.2	37.8	95.8	115.1
Total expenses	72.6	98.5	219.9	334.8
Income from unconsolidated investments	9.8	9.6	61.2	23.6
Income from consolidated subsidiaries	0.0	0.0	0.0	0.0
Non-operating income (expense)
Gain on sale of real estate	(1.9)	39.4	244.2	242.8
Acquisition-related expenses	(1.2)	(0.3)	(3.0)	(0.5)
Interest expense	(22.7)	(25.1)	(72.6)	(82.6)
Other income (loss)	(0.5)	0.5	(2.3)	1.6
Income before provision for income taxes	1.8	60.4	281.0	283.3
Benefit from (provision for) income taxes	(2.5)	(2.1)	(6.4)	(11.4)
Net income	(0.7)	58.3	274.6	271.9
Net loss (income) attributable to the noncontrolling interests	1.3	(0.8)	(96.0)	(59.9)
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	0.6	57.5	178.6	212.0
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Rental [Member]
Revenue
Total revenue	65.2	84.0	207.7	264.1
Expenses
Cost of goods and services	22.4	20.7	66.6	72.2
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Hotel [Member]
Revenue
Total revenue	25.1	43.5	62.9	117.6
Expenses
Cost of goods and services	17.3	30.6	47.6	90.8
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Sale of Real Estate [Member]
Revenue
Total revenue	0.0	6.5	1.1	48.7
Expenses
Cost of goods and services	0.0	5.8	1.2	45.6
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	0.6	0.8	1.7	2.8
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Commission and Marketing [Member]
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Reportable Legal Entities [Member] \| Non-guarantor Subsidiaries [Member] \| Compensation and Related [Member]
Expenses
Cost of goods and services	1.4	1.4	4.2	4.0
Elimination [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
General and administrative	0.0	0.0	0.0	0.0
Depreciation and amortization	0.0	0.0	0.0	0.0
Total expenses	0.0	0.0	0.0	0.0
Income from unconsolidated investments	0.0	0.0	0.0	0.0
Income from consolidated subsidiaries	(102.4)	(142.3)	(798.0)	(817.5)
Non-operating income (expense)
Gain on sale of real estate	0.0	0.0	0.0	0.0
Acquisition-related expenses	0.0	0.0	0.0	0.0
Interest expense	0.0	0.0	0.0	0.0
Other income (loss)	0.0	0.0	0.0	0.0
Income before provision for income taxes	(102.4)	(142.3)	(798.0)	(817.5)
Benefit from (provision for) income taxes		0.0	0.0	0.0
Net income	(102.4)	(142.3)	(798.0)	(817.5)
Net loss (income) attributable to the noncontrolling interests	0.0	0.0	0.0	0.0
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	(102.4)	(142.3)	(798.0)	(817.5)
Elimination [Member] \| Rental [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Elimination [Member] \| Hotel [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Elimination [Member] \| Sale of Real Estate [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Elimination [Member] \| Investment Management, Property Services and Research Fees [Member]
Revenue
Total revenue	0.0	0.0	0.0	0.0
Elimination [Member] \| Commission and Marketing [Member]
Expenses
Cost of goods and services	0.0	0.0	0.0	0.0
Elimination [Member] \| Compensation and Related [Member]
Expenses
Cost of goods and services	$ 0.0	$ 0.0	$ 0.0	$ 0.0

Income (Loss) from Consolidated Subsidiaries

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Income (Loss) From Unconsolidated Investments

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Total costs of sales and operating expenses for the period.

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- Definition

The net gain (loss) resulting from sales and other disposals of real estate owned for investment purposes.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of expenses related to the generation of investment income.

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Amount of Net Income (Loss) attributable to noncontrolling interest.

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