Investments (Tables)

3 Months Ended

Dec. 31, 2016

Investments [Abstract]

Summary of investments

Investments consisted of the following:

(in millions)	December 31, 2016		September 30, 2016
Investment securities, trading
SIPs	$	138.8	$	844.4
Debt and other equity securities	264.2		277.5
Total investment securities, trading	403.0		1,121.9
Investment securities, available-for-sale
SIPs	102.3		297.7
Debt and other equity securities	3.0		3.7
Total investment securities, available-for-sale	105.3		301.4
Investments in equity method investees	816.0		797.4
Other investments	188.5		195.9
Total	$	1,512.8	$	2,416.6

Summary of the gross unrealized gains and losses relating to investment securities, available-for-sale

Gross unrealized gains and losses relating to investment securities, available-for-sale were as follows:

(in millions)			Gross Unrealized
as of December 31, 2016	Cost Basis		Gains		Losses			Fair Value
SIPs	$	103.2	$	1.0	$	(1.9	)	$	102.3
Debt and other equity securities	2.9		0.1		—			3.0
Total	$	106.1	$	1.1	$	(1.9	)	$	105.3

(in millions)			Gross Unrealized
as of September 30, 2016	Cost Basis		Gains		Losses			Fair Value
SIPs	$	289.6	$	13.7	$	(5.6	)	$	297.7
Debt and other equity securities	3.6		0.1		—			3.7
Total	$	293.2	$	13.8	$	(5.6	)	$	301.4

Summary of gross unrealized losses and fair values of investment securities in a continuous unrealized loss position

Gross unrealized losses relating to investment securities, available-for-sale aggregated by length of time that individual securities have been in a continuous unrealized loss position were as follows:

	Less Than 12 Months					12 Months or Greater					Total
(in millions)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
as of December 31, 2016
SIPs	$	19.5	$	(1.1	)	$	5.2	$	(0.8	)	$	24.7	$	(1.9	)

	Less Than 12 Months					12 Months or Greater					Total
(in millions)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
as of September 30, 2016
SIPs	$	75.8	$	(4.3	)	$	18.0	$	(1.3	)	$	93.8	$	(5.6	)