Guarantor and Non-Guarantor Financial Statements (Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ (36.9)		$ (27.6)
Cash flows from investing activities:
Additions to loans	(158.6)		(8.2)
Collections of loans	0.2		0
Proceeds from sale of interest in an entity	0		26.7
Net proceeds from sale of real estate	10.0		3.4
Purchases of and additions to real estate	(367.7)		(15.6)
Distributions from unconsolidated investments	11.0		28.8
Contributions to unconsolidated investments	67.1		52.1
Investment in marketable securities	(4.5)		0
(Investments in) distributions from consolidated subsidiaries, net	0		0
Net cash used in investing activities	(576.7)		(17.0)
Cash flows from financing activities:
Borrowings under line of credit	90.0		35.0
Repayment of line of credit	(90.0)		(35.0)
Borrowings under investment debt	195.8		0
Borrowings under senior notes payable	297.2		0
Debt issue costs	(9.6)		(0.4)
Repayment of investment debt	(5.5)		(0.1)
Issuance of common stock	190.8		133.8
Dividends paid	(7.8)	[1]	(7.1)	[1]
Repurchase and retirement of common stock	(2.5)		0
Proceeds from the issuance of KWE shares, net	1,350.7		0
Intercompany receivables, net			0
Contributions from noncontrolling interests, excluding KWE	2.9		0
Distributions to noncontrolling interests	(2.8)		0
Net cash provided by financing activities	2,009.2		126.2
Effect of currency exchange rate changes on cash and cash equivalents	(0.7)		(4.1)
Net change in cash and cash equivalents	1,394.9		77.5
Cash and cash equivalents, end of period	1,573.1		198.4
Cash and cash equivalents, beginning of period	178.2		120.9
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(0.3)		0.1
Cash flows from investing activities:
Additions to loans	0		0
Collections of loans	0
Proceeds from sale of interest in an entity			0
Net proceeds from sale of real estate	0		0
Purchases of and additions to real estate	0		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	(180.2)		0.3
Net cash used in investing activities	(180.2)		0.3
Cash flows from financing activities:
Borrowings under line of credit	0		0
Repayment of line of credit	0		0
Borrowings under investment debt	0
Borrowings under senior notes payable	0
Debt issue costs	0		0
Repayment of investment debt	0		0
Issuance of common stock	190.8		133.8
Dividends paid	(7.8)		(7.1)
Repurchase and retirement of common stock	(2.5)
Proceeds from the issuance of KWE shares, net	0
Intercompany receivables, net			0
Contributions from noncontrolling interests, excluding KWE	0
Distributions to noncontrolling interests	0
Net cash provided by financing activities	180.5		126.7
Effect of currency exchange rate changes on cash and cash equivalents	0		0
Net change in cash and cash equivalents	0		127.1
Cash and cash equivalents, end of period	0		127.1
Cash and cash equivalents, beginning of period	0		0
Kennedy-Wilson, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(51.2)		(39.7)
Cash flows from investing activities:
Additions to loans	0		0
Collections of loans	0.1
Proceeds from sale of interest in an entity			0
Net proceeds from sale of real estate	0		0
Purchases of and additions to real estate	0		0
Distributions from unconsolidated investments	0		0
Contributions to unconsolidated investments	2.0		2.3
Investment in marketable securities	0
(Investments in) distributions from consolidated subsidiaries, net	(37.8)		13.7
Net cash used in investing activities	(39.7)		11.4
Cash flows from financing activities:
Borrowings under line of credit	90.0		35.0
Repayment of line of credit	(90.0)		(35.0)
Borrowings under investment debt	0
Borrowings under senior notes payable	297.2
Debt issue costs	(6.2)		(0.4)
Repayment of investment debt	0		0
Issuance of common stock	0		0
Dividends paid	0		0
Repurchase and retirement of common stock	0
Proceeds from the issuance of KWE shares, net	0
Intercompany receivables, net			(2.7)
Contributions from noncontrolling interests, excluding KWE	0
Distributions to noncontrolling interests	0
Net cash provided by financing activities	291.0		(3.1)
Effect of currency exchange rate changes on cash and cash equivalents	0		(2.4)
Net change in cash and cash equivalents	200.1		(33.8)
Cash and cash equivalents, end of period	248.3		30.7
Cash and cash equivalents, beginning of period	48.2		64.5
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(5.8)		8.3
Cash flows from investing activities:
Additions to loans	(5.7)		(8.2)
Collections of loans	0.1
Proceeds from sale of interest in an entity			26.7
Net proceeds from sale of real estate	0		3.4
Purchases of and additions to real estate	(13.4)		(0.8)
Distributions from unconsolidated investments	5.6		28.8
Contributions to unconsolidated investments	6.8		29.2
Investment in marketable securities	(4.5)
(Investments in) distributions from consolidated subsidiaries, net	(42.9)		(43.9)
Net cash used in investing activities	(67.6)		(23.2)
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
Borrowings under senior notes payable	0
Debt issue costs	(0.2)		0
Repayment of investment debt	0		0
Issuance of common stock	0		0
Dividends paid	0		0
Repurchase and retirement of common stock	0
Proceeds from the issuance of KWE shares, net	0
Intercompany receivables, net			0
Contributions from noncontrolling interests, excluding KWE	0
Distributions to noncontrolling interests	0
Net cash provided by financing activities	17.8		0
Effect of currency exchange rate changes on cash and cash equivalents	0		(0.5)
Net change in cash and cash equivalents	(55.6)		(15.4)
Cash and cash equivalents, end of period	21.6		23.1
Cash and cash equivalents, beginning of period	77.2		38.5
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	20.4		3.7
Cash flows from investing activities:
Additions to loans	(152.9)		0
Collections of loans	0
Proceeds from sale of interest in an entity			0
Net proceeds from sale of real estate	10.0		0
Purchases of and additions to real estate	(354.3)		(14.8)
Distributions from unconsolidated investments	5.4		0
Contributions to unconsolidated investments	58.3		20.6
Investment in marketable securities	0
(Investments in) distributions from consolidated subsidiaries, net	260.9		29.9
Net cash used in investing activities	(289.2)		(5.5)
Cash flows from financing activities:
Borrowings under line of credit	0		0
Repayment of line of credit	0		0
Borrowings under investment debt	177.8
Borrowings under senior notes payable	0
Debt issue costs	(3.2)		0
Repayment of investment debt	(5.5)		(0.1)
Issuance of common stock	0		0
Dividends paid	0		0
Repurchase and retirement of common stock	0
Proceeds from the issuance of KWE shares, net	1,350.7
Intercompany receivables, net			2.7
Contributions from noncontrolling interests, excluding KWE	2.9
Distributions to noncontrolling interests	(2.8)
Net cash provided by financing activities	1,519.9		2.6
Effect of currency exchange rate changes on cash and cash equivalents	(0.7)		(1.2)
Net change in cash and cash equivalents	1,250.4		(0.4)
Cash and cash equivalents, end of period	1,303.2		17.5
Cash and cash equivalents, beginning of period	$ 52.8		$ 17.9

[1] Common stock dividends are 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.