Investments (Tables)

3 Months Ended

Mar. 31, 2018

Investments [Abstract]

Marketable Securities

$ in millions	March 31, 2018	December 31, 2017
Equity investments:
Seed money	264.2	243.0
Investments related to deferred compensation plans	98.7	92.3
Other equity securities	18.5	11.3
Available-for-sale debt investments:
CLOs	4.9	6.0
Other debt securities	6.2	9.9
Equity method investments	286.6	277.3
Foreign time deposits	28.7	28.6
Other	5.8	6.2
Total investments	713.6	674.6

Realized Gains Losses Available-For-Sale Securities

Realized gains and losses recognized in the Condensed Consolidated Statements of Income during the period from investments classified as available-for-sale are as follows:

	For the three months ended March 31, 2018
$ in millions	Proceeds from Sales	Gross Realized Gains	Gross Realized Losses
CLOs	2.6	—	—
Other debt securities	0.2	—	(0.1	)
	2.8	—	(0.1	)

	For the three months ended March 31, 2017
$ in millions	Proceeds from Sales	Gross Realized Gains	Gross Realized Losses
Seed money	34.2	1.6	(1.3	)
CLOs	2.0	0.3	—
Other debt securities	7.6	—	—
	43.8	1.9	(1.3	)

Gross Unrealized Holding Gains And Losses Recognized In Other Accumulated Comprehensive Income From Available-For-Sale Investments

Gross unrealized holding gains and losses recognized in other accumulated other comprehensive income/(loss) from available-for-sale debt investments are presented in the tables below:

	March 31, 2018
$ in millions	Cost	Gross Unrealized Holding Gains	Gross Unrealized Holding Losses		Fair Value
CLOs	3.5	1.4	—		4.9
Other debt securities	6.4	—	(0.2	)	6.2
	9.9	1.4	(0.2	)	11.1

	December 31, 2017
$ in millions	Cost	Gross Unrealized Holding Gains	Gross Unrealized Holding Losses		Fair Value
Seed money	65.1	5.5	(1.3	)	69.3
CLOs	4.9	1.1	—		6.0
Other debt securities	9.9	—	—		9.9
	79.9	6.6	(1.3	)	85.2

Breakdown Of Available-For-Sale Investments with Unrealized Losses

At December 31, 2017: 50 seed money funds had incurred gross unrealized holding losses. The following table provides a breakdown of the unrealized losses.

	December 31, 2017
$ in millions	Fair Value	Gross Unrealized Losses
Less than 12 months	9.4	(0.8	)
12 months or greater	15.0	(0.5	)
Total	24.4	(1.3	)

Held-to-maturity Securities [Table Text Block]

Available-for-sale debt securities as of March 31, 2018 by maturity, are set out below:

	Available-for-Sale (Fair Value)
Less than one year	6.2
One to five years	0.5
Five to ten years	4.4
Greater than ten years	—
Total available-for-sale	11.1