Amount of unrealized holding gain before loss recognized in the income statement for investments in trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Short term investments	$ 10.7		$ 22.0
Clinton Group
Schedule of Available-for-sale Securities [Line Items]
Short term investments	9.5		$ 19.5
Clinton Group \| Other (income) expense
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss	$ 0.1	$ 1.6