Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities:
Net income	$ 459.3	$ 312.1
Adjustments to reconcile net income to net cash (used in)/provided by operating activities:
Amortization and depreciation	72.5	95.3
Share-based compensation expense	102.9	86.0
Gains on disposal of property, equipment, and software, net	(0.5)	0
Purchase of trading investments	(7,573.2)	(8,120.7)
Proceeds from sale of trading investments	7,564.6	8,103.6
Other gains and losses, net	(29.3)	5.8
(Gains)/losses of consolidated investment products, net	69.9	243.3
Tax benefit from share-based compensation	47.7	74.2
Excess tax benefits from share-based compensation	(13.7)	(15.8)
Equity in earnings of unconsolidated affiliates	(21.8)	(25.6)
Dividends from unconsolidated affiliates	14.7	20.1
Changes in operating assets and liabilities:
(Increase)/decrease in cash held by consolidated investment products	(296.0)	296.3
(Increase)/decrease in receivables	151.9	41.3
Increase/(decrease) in payables	(231.3)	(473.9)
Net cash (used in)/provided by operating activities	317.7	642.0
Investing activities:
Purchase of property and equipment	(68.4)	(60.6)
Disposal of property and equipment	0.6	12.6
Purchase of available-for-sale investments	(73.9)	(31.1)
Proceeds from sale of available-for-sale investments	32.9	50.2
Purchase of investments by consolidated investment products	(2,338.9)	(2,594.2)
Proceeds from sale of investments by consolidated investment products	2,484.5	3,035.3
Purchase of other investments	(87.7)	(102.3)
Proceeds from sale of other investments	63.4	35.7
Returns of capital and distributions from unconsolidated partnership investments	12.2	28.5
Acquisition of businesses	0	(14.9)
Acquisition earn-out payments	(5.6)	(5.4)
sale of management contracts	16.4	0
Net cash (used in)/provided by investing activities	35.5	353.8
Financing activities:
Proceeds from exercises of share options	17.2	11.0
Purchases of treasury shares	(190.0)	(333.0)
Dividends paid	(211.5)	(165.0)
Excess tax benefits from share-based compensation	13.7	15.8
Capital invested into consolidated investment products	19.4	27.9
Capital distributed by consolidated investment products	(122.0)	(158.8)
Net borrowings/(repayments) of debt of consolidated investment products	255.4	(434.9)
Net borrowings/(repayments) under credit facility	215.5	74.0
Repayments of senior notes	(215.1)	0
Acquisition of interest in consolidated investment products	0	(12.3)
Net cash provided by/(used in) financing activities	(217.4)	(975.3)
(Decrease)/increase in cash and cash equivalents	135.8	20.5
Foreign exchange movement on cash and cash equivalents	16.9	(4.0)
Cash and cash equivalents, beginning of period	727.4	740.5
Cash and cash equivalents, end of period	880.1	757.0
Supplemental Cash Flow Information:
Interest paid	(39.0)	(39.1)
Interest received	3.5	8.2
Taxes paid	$ (154.4)	$ (137.7)