Other Assets (Details) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Other Assets [Abstract]
Loan fees, net of accumulated amortization of $10.7 and $5.0 at September 30, 2015 and December 31, 2014, respectively	$ 44.1	$ 36.0
Deferred tax asset, net	36.1	27.6
Other, net of accumulated amortization of $2.7 and $1.8 at September 30, 2015 and December 31, 2014, respectively	33.5	25.8
Hedge Assets	32.7	30.6
Goodwill	23.9	23.9
Prepaid expenses	15.0	11.2
Deposits	3.5	49.9
Marketable securities	0.3	6.5
Other Assets	310.5	305.1
Accumulated amortization, loan fees	10.7	5.0
Accumulated amortization, other	2.7	1.8
Investments in and advances to consolidated subsidiaries	$ 0.0	0.0
KWE [Member]
Other Assets [Abstract]
Shares in KWE (in shares)	24.0
KWE [Member] | Marketable Securities [Member]
Other Assets [Abstract]
Investments in and advances to consolidated subsidiaries	$ 413.5
Furniture and Fixtures [Member]
Other Assets [Abstract]
Office furniture and equipment net of accumulated depreciation of $9.1 and $5.7 at September 30, 2015 and December 31, 2014, respectively	20.5	22.0
Accumulated amortization, office furniture and equipment	9.1	5.7
Above Market Leases [Member]
Other Assets [Abstract]
Above-market leases, net of accumulated amortization of $16.3 and $6.7 at September 30, 2015 and December 31, 2014, respectively	100.9	71.6
Accumulated amortization, above-market leases	$ 16.3	$ 6.7