Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 28.3	$ 5.1	$ 29.9	$ (4.3)	$ (20.5)	$ (3.0)	$ 63.7	$ 49.8	$ 59.0	$ 90.1	$ 13.9
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities									0.1	(0.2)	0.0
Unrealized foreign currency translation loss									(138.3)	(46.4)	(9.3)
Amounts reclassified from accumulated other comprehensive income									9.7	(7.1)	2.8
Unrealized foreign currency derivative contracts gain									6.3	16.3	3.1
Total other comprehensive loss for the period									(122.2)	(37.4)	(3.4)
Comprehensive (loss) income									(63.2)	52.7	10.5
Comprehensive income attributable to noncontrolling interests									118.4	(15.6)	(20.3)
Comprehensive income (loss) attributable to Kennedy-Wilson Holdings, Inc.									$ 55.2	$ 37.1	$ (9.8)