Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 167.3	$ 21.8	$ 166.3	$ 22.8
Other comprehensive income (loss), net of tax:
Unrealized gain on marketable securities	0.0	0.1	0.0	0.1
Unrealized foreign currency translation (loss) gain	(74.3)	99.6	(38.9)	120.8
Amounts reclassified out of AOCI during the period	13.2	0.0	13.1	0.0
Unrealized currency derivative contracts gain (loss)	29.6	(41.5)	22.2	(32.8)
Total other comprehensive (loss) income for the period	(31.5)	58.2	(3.6)	88.1
Comprehensive income	135.8	80.0	162.7	110.9
Comprehensive (income) loss attributable to noncontrolling interests	(58.7)	(61.0)	(65.1)	(85.9)
Comprehensive income attributable to Kennedy-Wilson Holdings, Inc. common shareholders	$ 77.1	$ 19.0	$ 97.6	$ 25.0