Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of investments

Investments are as follows (in millions):

	Carrying Value
	December 31, 2017		December 31, 2016
Available-for-sale securities:
State Street Corporation	$	—	$	169.6
Other available-for-sale securities	11.8		10.9
	11.8		180.5
Other:
Trading securities	33.6		7.9
Seed capital investments, at fair value	12.1		61.0
Cost method, private equity and other investments	142.2		128.0
	187.9		196.9
Total investments	$	199.7	$	377.4

Schedule of reconciliation of available-for-sale securities from book cost basis to market value

Certain information related to our available-for-sale securities is as follows (in millions):

	December 31,
	2017		2016
Book cost basis	$	8.6	$	28.4
Gross unrealized gains	3.2		152.1
Market value	$	11.8	$	180.5