Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Short term investments	$ 2.7		$ 22.0
Clinton Group
Schedule of Available-for-sale Securities [Line Items]
Short term investments	2.2		$ 19.5
Decrease in short term investment balance	17.3
Redemptions	16.9
Accrued fees		$ 0.5
Clinton Group | Other (income) expense
Schedule of Available-for-sale Securities [Line Items]
Unrealized holding loss	0.4	$ 0.7
GBAM Fund
Schedule of Available-for-sale Securities [Line Items]
Short term investments	$ 0.2