Fair Value Measurements (Derivatives Financial Instruments) (Details) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended	9 Months Ended					3 Months Ended	9 Months Ended							3 Months Ended		9 Months Ended										3 Months Ended		9 Months Ended						3 Months Ended		9 Months Ended
	Sep. 30, 2014 USD ($)		Sep. 30, 2014 USD ($)		Sep. 30, 2014 Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 Euro Member Countries, Euro Foreign Exchange Forward [Member] USD ($)	Sep. 30, 2014 Euro Member Countries, Euro Foreign Exchange Forward [Member] EUR (€)	Sep. 30, 2014 Euro Member Countries, Euro Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)	Sep. 30, 2014 Euro Member Countries, Euro Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)	Sep. 30, 2014 Euro Member Countries, Euro Minimum [Member] Foreign Exchange Forward [Member]	Sep. 30, 2014 Euro Member Countries, Euro Maximum [Member] Foreign Exchange Forward [Member]	Sep. 30, 2014 United Kingdom, Pounds Foreign Exchange Forward [Member] USD ($)	Sep. 30, 2014 United Kingdom, Pounds Foreign Exchange Forward [Member] GBP (£)	Sep. 30, 2014 United Kingdom, Pounds Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)	Sep. 30, 2014 United Kingdom, Pounds Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)	Sep. 30, 2014 United Kingdom, Pounds Minimum [Member] Foreign Exchange Forward [Member]	Sep. 30, 2014 United Kingdom, Pounds Maximum [Member] Foreign Exchange Forward [Member]	Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Foreign Exchange Forward [Member] USD ($)		Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Foreign Exchange Forward [Member] EUR (€)		Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Minimum [Member] Foreign Exchange Forward [Member]		Sep. 30, 2014 KWE [Member] Euro Member Countries, Euro Maximum [Member] Foreign Exchange Forward [Member]		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Forward [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Forward [Member] JPY (¥)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Forward [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Option [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Option [Member] JPY (¥)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Option [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Foreign Exchange Option [Member] Other Comprehensive Income (Loss) [Member] USD ($)		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Minimum [Member] Foreign Exchange Option [Member]		Sep. 30, 2014 KW Residential, LLC [Member] Japan, Yen Maximum [Member] Foreign Exchange Option [Member]
Derivative [Line Items]
Notional Amount										€ 93.5						£ 95.5							€ 185.0	[1]											¥ 7,500.0	[2]							¥ 10,953.0	[2],[3]
Forward Rate/Strike Price													1.240	1.4471					1.6356	1.6491									0.8021	[1]	0.8621	[1]	91.645	[2]	91.645	[2]													108.4500	[2],[3]	110.6200	[2],[3]
Fair Value	25.3	[4]	25.3	[4]					3.7						1.6						4.7	[1]											12.7	[2]							2.6	[2],[3]
Change in Unrealized Gains (Losses)					28.5	[4]	24.6	[4]			9.0	9.1					4.4	1.6							6.0	[1]	4.8	[1]									8.7	[2]	8.7	[2]					0.4	[2],[3]	0.4	[2],[3]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 0.1		$ 0.1

[1] Hedge is held by KWE on its wholly-owned subsidiaries

[2] Hedge is held by KWR on its wholly-owned subsidiaries

[3] For the three and nine months ended September 30, 2014, $0.1 million recognized through results of operations due to portion of hedge not designated as a net investment hedge

[4] Hedges are presented gross in the consolidated balance sheet. Hedge assets are included in other assets and hedge liabilities are included in other liabilities.