Guarantor and Non-Guarantor Financial Statements (Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash from (used in) operating activities	$ 65.1		$ (23.9)
Cash flows from investing activities:
Additions to loans	(373.3)		(14.3)
Collections of loans	18.7		33.6
Net proceeds from sale of real estate	15.0		9.0
Purchases of and additions to real estate	(1,289.8)		(108.3)
Proceeds from sale of marketable securities	0		10.0
Distributions from unconsolidated investments	55.6		75.3
Contributions to unconsolidated investments	(106.0)		(200.5)
Investment in marketable securities	(6.9)		0
(Investments in) distributions from consolidated subsidiaries, net	0		0
Net cash used in investing activities	(1,686.7)		(195.2)
Cash flows from financing activities:
Borrowings under line of credit	90.0		85.0
Repayment of line of credit	(90.0)		(55.0)
Borrowings under investment debt	295.2		68.3
Borrowings under senior notes payable	297.2		0
Repayment of investment debt	(14.0)		(0.6)
Debt issue costs	(11.3)		(0.9)
Issuance of common stock	190.7		153.9
Repurchase and retirement of common stock	(2.6)		0
Repurchase of warrants	0		(1.4)
Proceeds from the issuance of KWE shares, net	1,351.1		0
Dividends paid	(18.1)	[1]	(9.1)	[1]
Change in restricted cash	(42.6)		0
Acquisition of KWE shares from noncontrolling interest holders	(16.8)		0
Contributions from noncontrolling interests, excluding KWE	8.6		0.6
Distributions to noncontrolling interests	(13.5)		(0.2)
Intercompany receivables, net			0
Net cash provided by financing activities	2,023.9		240.6
Effect of currency exchange rate changes on cash and cash equivalents	19.2		(2.7)
Net change in cash and cash equivalents	421.5		18.8
Cash and cash equivalents, beginning of period	178.2		120.9
Cash and cash equivalents, end of period	599.7		139.7
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash from (used in) operating activities	1.8		(0.2)
Cash flows from investing activities:
Additions to loans	0		0
Collections of loans	0		0
Net proceeds from sale of real estate	0		0
Purchases of and additions to real estate	0		0
Proceeds from sale of marketable securities			0
Distributions from unconsolidated investments	0		0
Contributions to unconsolidated investments	0		0
Investment in marketable securities	0
(Investments in) distributions from consolidated subsidiaries, net	(171.9)		(35.8)
Net cash used in investing activities	(171.9)		(35.8)
Cash flows from financing activities:
Borrowings under line of credit	0		0
Repayment of line of credit	0		0
Borrowings under investment debt	0		0
Borrowings under senior notes payable	0
Repayment of investment debt	0		0
Debt issue costs	0		0
Issuance of common stock	190.7		153.9
Repurchase and retirement of common stock	(2.6)
Repurchase of warrants			(1.4)
Proceeds from the issuance of KWE shares, net	0
Dividends paid	(18.1)		(9.1)
Change in restricted cash	0
Acquisition of KWE shares from noncontrolling interest holders	0
Contributions from noncontrolling interests, excluding KWE	0		0
Distributions to noncontrolling interests	0		0
Intercompany receivables, net			0
Net cash provided by financing activities	170.0		143.4
Effect of currency exchange rate changes on cash and cash equivalents	0		0
Net change in cash and cash equivalents	(0.1)		107.4
Cash and cash equivalents, beginning of period	0		0
Cash and cash equivalents, end of period	(0.1)		107.4
Kennedy-Wilson, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash from (used in) operating activities	(75.3)		(46.4)
Cash flows from investing activities:
Additions to loans	0		(6.0)
Collections of loans	0		0
Net proceeds from sale of real estate	0		0
Purchases of and additions to real estate	0		0
Proceeds from sale of marketable securities			10.0
Distributions from unconsolidated investments	0.2		0.2
Contributions to unconsolidated investments	(2.0)		(2.3)
Investment in marketable securities	0
(Investments in) distributions from consolidated subsidiaries, net	67.1		(24.6)
Net cash used in investing activities	65.3		(22.7)
Cash flows from financing activities:
Borrowings under line of credit	90.0		85.0
Repayment of line of credit	(90.0)		(55.0)
Borrowings under investment debt	0		0
Borrowings under senior notes payable	297.2
Repayment of investment debt	0		0
Debt issue costs	(7.0)		(0.9)
Issuance of common stock	0		0
Repurchase and retirement of common stock	0
Repurchase of warrants			0
Proceeds from the issuance of KWE shares, net	0
Dividends paid	0		0
Change in restricted cash	0
Acquisition of KWE shares from noncontrolling interest holders	0
Contributions from noncontrolling interests, excluding KWE	0		0
Distributions to noncontrolling interests	0		0
Intercompany receivables, net			(19.7)
Net cash provided by financing activities	290.2		9.4
Effect of currency exchange rate changes on cash and cash equivalents	0		(0.1)
Net change in cash and cash equivalents	280.2		(59.8)
Cash and cash equivalents, beginning of period	48.2		64.5
Cash and cash equivalents, end of period	328.4		4.7
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash from (used in) operating activities	58.5		16.8
Cash flows from investing activities:
Additions to loans	(5.7)		(8.3)
Collections of loans	0.2		33.6
Net proceeds from sale of real estate	0		9.0
Purchases of and additions to real estate	(4.4)		(30.8)
Proceeds from sale of marketable securities			0
Distributions from unconsolidated investments	44.4		72.4
Contributions to unconsolidated investments	(19.1)		(162.7)
Investment in marketable securities	(6.9)
(Investments in) distributions from consolidated subsidiaries, net	(141.4)		26.5
Net cash used in investing activities	(132.9)		(60.3)
Cash flows from financing activities:
Borrowings under line of credit	0		0
Repayment of line of credit	0		0
Borrowings under investment debt	18.0		18.7
Borrowings under senior notes payable	0
Repayment of investment debt	0		0
Debt issue costs	(0.4)		0
Issuance of common stock	0		0
Repurchase and retirement of common stock	0
Repurchase of warrants			0
Proceeds from the issuance of KWE shares, net	0
Dividends paid	0		0
Change in restricted cash	0
Acquisition of KWE shares from noncontrolling interest holders	0
Contributions from noncontrolling interests, excluding KWE	0		0
Distributions to noncontrolling interests	0		0
Intercompany receivables, net			0.1
Net cash provided by financing activities	17.6		18.8
Effect of currency exchange rate changes on cash and cash equivalents	0		(1.4)
Net change in cash and cash equivalents	(56.8)		(26.1)
Cash and cash equivalents, beginning of period	77.2		38.5
Cash and cash equivalents, end of period	20.4		12.4
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash from (used in) operating activities	80.1		5.9
Cash flows from investing activities:
Additions to loans	(367.6)		0
Collections of loans	18.5		0
Net proceeds from sale of real estate	15.0		0
Purchases of and additions to real estate	(1,285.4)		(77.5)
Proceeds from sale of marketable securities			0
Distributions from unconsolidated investments	11.0		2.7
Contributions to unconsolidated investments	(84.9)		(35.5)
Investment in marketable securities	0
(Investments in) distributions from consolidated subsidiaries, net	246.2		33.9
Net cash used in investing activities	(1,447.2)		(76.4)
Cash flows from financing activities:
Borrowings under line of credit	0		0
Repayment of line of credit	0		0
Borrowings under investment debt	277.2		49.6
Borrowings under senior notes payable	0
Repayment of investment debt	(14.0)		(0.6)
Debt issue costs	(3.9)		0
Issuance of common stock	0		0
Repurchase and retirement of common stock	0
Repurchase of warrants			0
Proceeds from the issuance of KWE shares, net	1,351.1
Dividends paid	0		0
Change in restricted cash	(42.6)
Acquisition of KWE shares from noncontrolling interest holders	(16.8)
Contributions from noncontrolling interests, excluding KWE	8.6		0.6
Distributions to noncontrolling interests	(13.5)		(0.2)
Intercompany receivables, net			19.6
Net cash provided by financing activities	1,546.1		69.0
Effect of currency exchange rate changes on cash and cash equivalents	19.2		(1.2)
Net change in cash and cash equivalents	198.2		(2.7)
Cash and cash equivalents, beginning of period	52.8		17.9
Cash and cash equivalents, end of period	$ 251.0		$ 15.2

[1] Common stock dividends were declared at the end of each quarter and paid in the following quarter. The amount declared and not paid is accrued on the consolidated balance sheet.