Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 142.3	$ 143.0	$ 143.7	$ 140.7	$ 178.7	$ 185.8	$ 218.3	$ 190.7	$ 569.7	$ 772.4	$ 801.8
Expenses
General and administrative									42.4	50.8	42.2
Depreciation and amortization									187.6	206.1	212.5
Total expenses	155.0	147.9	143.8	153.1	187.8	177.2	212.5	188.9	599.8	766.4	770.8
Income from unconsolidated investments, net of depreciation and amortization	177.9	34.5	162.2	18.0	66.3	11.2	190.9	(5.4)	179.7	78.7	77.8
Gain on sale of real estate, net									434.4	371.8	226.7
Gain on sale of business									0.0	40.4	0.0
Acquisition-related expenses									(6.8)	(1.7)	(4.4)
Interest expense									(215.1)	(238.2)	(217.7)
Other income									0.4	13.1	8.3
Income before (provision for) benefit from income taxes	165.2	29.6	162.1	5.6	57.2	19.8	196.7	(3.6)	362.5	270.1	121.7
(Provision for) benefit from income taxes	(6.3)	(10.2)	(20.9)	(4.0)	(24.3)	(6.9)	(29.4)	2.6	(41.4)	(58.0)	16.3
Net income	158.9	19.4	141.2	1.6	32.9	12.9	167.3	(1.0)	321.1	212.1	138.0
Net income attributable to the noncontrolling interests	1.6	1.3	(90.4)	(6.9)	(2.2)	(0.8)	(57.7)	(1.4)	(94.4)	(62.1)	(37.5)
Preferred dividends and accretion of preferred stock issuance costs	(2.6)	0.0	0.0	0.0					(2.6)	0.0	0.0
Net income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	$ 157.9	$ 20.7	$ 50.8	$ (5.3)	$ 30.7	$ 12.1	$ 109.6	$ (2.4)	$ 224.1	$ 150.0	$ 100.5
Basic Earnings per share
Income per basic (in dollars per share)	$ 1.13	$ 0.15	$ 0.36	$ (0.04)	$ 0.21	$ 0.09	$ 0.77	$ (0.02)	$ 1.60	$ 1.04	$ 0.83
Weighted average shares outstanding for basic (in shares)									139,729,573	142,895,472	119,147,192
Diluted Earnings per share
Income per diluted (in dollars per share)	$ 1.12	$ 0.15	$ 0.36	$ (0.04)	$ 0.21	$ 0.09	$ 0.77	$ (0.02)	$ 1.58	$ 1.04	$ 0.83
Weighted average shares outstanding for diluted (in shares)									141,501,323	144,753,421	119,147,192
Dividends declared per common share (in dollars per share)									$ 0.85	$ 0.78	$ 0.70
Rental [Member]
Total revenue									$ 447.4	$ 514.6	$ 504.7
Expenses
Cost of goods sold									152.9	160.8	151.2
Hotel [Member]
Total revenue									80.5	155.7	127.5
Expenses
Cost of goods sold									60.1	121.5	100.3
Sale of real estate [Member]
Total revenue									1.1	56.8	111.5
Expenses
Cost of goods sold									1.2	52.5	80.2
Investment management, property services and research fees [Member]
Total revenue									40.7	45.3	42.9
Loan purchases, loan originations, and other [Member]
Total revenue									0.0	0.0	15.2
Commission and marketing [Member]
Expenses
Cost of goods sold									3.8	5.9	7.2
Compensation and related [Member]
Expenses
Cost of goods sold									$ 151.8	$ 168.8	$ 177.2