SEGMENT INFORMATION - Segment Information, by Segment (Details) $ in Millions		3 Months Ended		12 Months Ended
		Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment				2
Revenue
Total revenue				$ 540.0	$ 453.6	$ 454.0
Principal co-investments				199.5	271.1	78.3
Performance allocations				(21.1)	117.9	2.7
Income from unconsolidated investments		$ 178.4	$ 389.0	178.4	389.0	81.0
Gain on sale of real estate, net				103.7	412.7	338.0
Expenses
Share-based compensation				29.0	28.7	32.3
Performance allocation compensation				(4.3)	42.0	0.2
General and administrative				37.2	33.3	34.6
Depreciation and amortization				172.9	166.3	179.6
Total expenses				526.8	549.6	508.1
Non-operating income (expense)
Interest expense				(220.8)	(192.4)	(201.9)
Gain (loss) on early extinguishment of debt				27.5	(45.7)	(9.3)
Other income (loss)				36.1	(5.0)	(2.3)
Provision for income taxes				(36.2)	(126.2)	(43.6)
Net income				101.9	336.4	107.8
Net (income) loss attributable to the noncontrolling interests				(8.2)	(6.0)	2.3
Preferred dividends				(28.9)	(17.2)	(17.2)
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders				64.8	313.2	92.9
Assets
Total assets	[1]	8,271.8	7,876.5	8,271.8	7,876.5
Expenditures for long lived assets
Investments				(569.1)	(1,271.0)	(264.2)
Corporate
Revenue
Total revenue				1.7	2.1	10.6
Principal co-investments				0.0	0.0	0.0
Performance allocations				0.0	0.0	0.0
Income from unconsolidated investments				0.0	0.0	0.0
Gain on sale of real estate, net				0.0	0.0	0.0
Expenses
Share-based compensation				29.0	28.7	32.3
Performance allocation compensation				0.0	0.0	0.0
General and administrative				7.7	6.3	8.1
Depreciation and amortization				0.0	0.0	0.0
Total expenses				61.9	68.1	71.8
Non-operating income (expense)
Gain (loss) on early extinguishment of debt				0.0	(26.5)	0.0
Other income (loss)				15.3	(0.3)	(0.9)
Provision for income taxes				(15.2)	(103.2)	(25.2)
Net income				(152.7)	(269.3)	(156.8)
Net (income) loss attributable to the noncontrolling interests				0.0	0.0	0.0
Preferred dividends				(28.9)	(17.2)	(17.2)
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders				(181.6)	(286.5)	(174.0)
Assets
Total assets		200.2	324.7	200.2	324.7
Rental
Revenue
Total revenue				434.9	390.5	403.9
Expenses
Cost of goods sold				151.2	132.7	135.7
Rental | Corporate
Revenue
Total revenue				0.0	0.0	0.0
Expenses
Cost of goods sold				0.0	0.0	0.0
Hotel
Revenue
Total revenue				46.9	17.1	13.9
Expenses
Cost of goods sold				29.5	12.7	13.8
Hotel | Corporate
Revenue
Total revenue				0.0	0.0	0.0
Expenses
Cost of goods sold				0.0	0.0	0.0
Property service fees
Revenue
Total revenue				1.7	2.1	10.6
Property service fees | Corporate
Revenue
Total revenue				1.7	2.1	10.6
Loans and other
Revenue
Total revenue				11.7	8.6	3.1
Loans and other | Corporate
Revenue
Total revenue				0.0	0.0	0.0
Investment management fees
Revenue
Total revenue				44.8	35.3	22.5
Investment management fees | Corporate
Revenue
Total revenue					0.0	0.0
Compensation and related
Expenses
Cost of goods sold				111.3	133.9	111.9
Compensation and related | Corporate
Expenses
Cost of goods sold				25.2	33.1	31.4
Co-Investments | Operating Segments
Revenue
Total revenue				56.5	43.9	25.6
Principal co-investments				199.5	271.1	78.3
Performance allocations				(21.1)	117.9	2.7
Income from unconsolidated investments				178.4	389.0	81.0
Gain on sale of real estate, net				0.0	0.0	0.0
Expenses
Share-based compensation				0.0	0.0	0.0
Performance allocation compensation				(4.3)	42.0	0.2
General and administrative				14.8	8.5	5.9
Depreciation and amortization				0.0	0.0	0.0
Total expenses				55.1	90.9	26.9
Non-operating income (expense)
Interest expense				0.0	0.0	0.0
Gain (loss) on early extinguishment of debt				0.0	0.0	0.0
Other income (loss)				0.0	0.0	0.0
Provision for income taxes				0.0	0.0	0.0
Net income				179.8	342.0	79.7
Net (income) loss attributable to the noncontrolling interests				0.0	0.0	0.0
Preferred dividends				0.0	0.0	0.0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders				179.8	342.0	79.7
Assets
Total assets		2,387.5	2,077.9	2,387.5	2,077.9
Co-Investments | Corporate
Non-operating income (expense)
Interest expense				(92.6)	(73.3)	(69.5)
Co-Investments | Rental | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Expenses
Cost of goods sold				0.0	0.0	0.0
Co-Investments | Hotel | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Expenses
Cost of goods sold				0.0	0.0	0.0
Co-Investments | Property service fees | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Co-Investments | Loans and other | Operating Segments
Revenue
Total revenue				11.7	8.6	3.1
Co-Investments | Investment management fees | Operating Segments
Revenue
Total revenue				44.8	35.3	22.5
Co-Investments | Compensation and related | Operating Segments
Expenses
Cost of goods sold				44.6	40.4	20.8
Consolidated | Operating Segments
Revenue
Total revenue				481.8	407.6	417.8
Principal co-investments				0.0	0.0	0.0
Performance allocations				0.0	0.0	0.0
Income from unconsolidated investments				0.0	0.0	0.0
Gain on sale of real estate, net				103.7	412.7	338.0
Expenses
Share-based compensation				0.0	0.0	0.0
Performance allocation compensation				0.0	0.0	0.0
General and administrative				14.7	18.5	20.6
Depreciation and amortization				172.9	166.3	179.6
Total expenses				409.8	390.6	409.4
Non-operating income (expense)
Interest expense				(128.2)	(119.1)	(132.4)
Gain (loss) on early extinguishment of debt				27.5	(19.2)	(9.3)
Other income (loss)				20.8	(4.7)	(1.4)
Provision for income taxes				(21.0)	(23.0)	(18.4)
Net income				74.8	263.7	184.9
Net (income) loss attributable to the noncontrolling interests				(8.2)	(6.0)	2.3
Preferred dividends				0.0	0.0	0.0
Net income (loss) attributable to Kennedy-Wilson Holdings, Inc. common shareholders				66.6	257.7	187.2
Assets
Total assets		$ 5,684.1	$ 5,473.9	5,684.1	5,473.9
Consolidated | Rental | Operating Segments
Revenue
Total revenue				434.9	390.5	403.9
Expenses
Cost of goods sold				151.2	132.7	135.7
Consolidated | Hotel | Operating Segments
Revenue
Total revenue				46.9	17.1	13.9
Expenses
Cost of goods sold				29.5	12.7	13.8
Consolidated | Property service fees | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Consolidated | Loans and other | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Consolidated | Investment management fees | Operating Segments
Revenue
Total revenue				0.0	0.0	0.0
Consolidated | Compensation and related | Operating Segments
Expenses
Cost of goods sold				$ 41.5	$ 60.4	$ 59.7
Minimum | Co-Investments
Segment Reporting Information [Line Items]
Average ownership interest in investments		5.00%		5.00%
Maximum | Co-Investments
Segment Reporting Information [Line Items]
Average ownership interest in investments		50.00%		50.00%

[1] The assets and liabilities as of December 31, 2022 include $169.8 million (including cash held by consolidated investments of $6.1 million and real estate and acquired in place lease values, net of accumulated depreciation and amortization of $137.8 million) and $82.4 million (including investment debt of $51.2 million), respectively, from consolidated variable interest entities ("VIEs"). The assets and liabilities as of December 31, 2021 include $189.6 million (including cash held by consolidated investments of $11.5 million and real estate and acquired in place lease values, net of accumulated depreciation and amortization of $152.8 million) and $129.2 million (including investment debt of $103.3 million), respectively, from VIEs. These assets can only be used to settle obligations of the consolidated VIEs, and the liabilities do not have recourse to the Company.