Consolidated Statements Of Changes In Equity (USD $) In Millions, unless otherwise specified	Total		Common Shares [Member]	Additional Paid-In-Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Retained Earnings Appropriated For Investors In Consolidated Investment Products [Member]	Accumulated Other Comprehensive Income [Member]	Total Equity Attributable to Common Shareholders [Member]	Noncontrolling Interests In Consolidated Entities [Member]	As Adjusted [Member]	As Adjusted [Member] Common Shares [Member]	As Adjusted [Member] Additional Paid-In-Capital [Member]	As Adjusted [Member] Treasury Stock [Member]	As Adjusted [Member] Retained Earnings [Member]	As Adjusted [Member] Retained Earnings Appropriated For Investors In Consolidated Investment Products [Member]	As Adjusted [Member] Accumulated Other Comprehensive Income [Member]	As Adjusted [Member] Total Equity Attributable to Common Shareholders [Member]	As Adjusted [Member] Noncontrolling Interests In Consolidated Entities [Member]
Beginning balance, value at Dec. 31, 2008	$ 6,596.2		$ 85.3	$ 5,352.6	$ (1,128.9)	$ 1,476.3		$ (95.8)	$ 5,689.5	$ 906.7
Adoption of guidance now encompassed in ASC Topic 810	274.3		0	0	0	5.2	274.3	(5.2)	274.3	0
Net income	209.3					322.5			322.5	(113.2)
Other comprehensive income:
Currency translation differences on investments in overseas subsidiaries	488.3	[1]						488.3	488.3
Change in accumulated OCI related to employee benefit plans	(15.1)							(15.1)	(15.1)
Change in net unrealized gains on available-for-sale investments	14.6							14.6	14.6
Adoption of guidance now encompassed in ASC Topic 320	(1.5)		0	0	0	0		(1.5)	(1.5)	0
Tax impacts of changes in accumulated other comprehensive income balances	3.1							3.1	3.1
Total comprehensive income/(loss)	698.7								811.9	(113.2)
Adoption of guidance now encompassed in ASC Topic 320	1.5		0	0	0	1.5		0	1.5	0
Change in noncontrolling interests in consolidated entities, net	(84.2)									(84.2)
Issuance of new shares	441.8		6.6	435.2					441.8
Dividends	(168.9)					(168.9)			(168.9)
Employee share plans:
Share-based compensation	90.8			90.8					90.8
Vested shares				(127.6)	127.6
Exercise of options	80.3			(51.5)	131.8				80.3
Tax impact of share-based payment	9.4			9.4					9.4
Modification of share-based payment awards	(13.0)			(13.0)
Purchase of shares	(22.9)				(22.9)				(22.9)
Acquisition of remaining noncontrolling interest in subsidiary	(8.9)			(7.5)					(7.5)	(1.4)
Ending Balance, value at Dec. 31, 2009	7,620.8		91.9	5,688.4	(892.4)	1,631.4	0	393.6	6,912.9	707.9	7,895.1	91.9	5,688.4	(892.4)	1,636.6	274.3	388.4	7,187.2	707.9
Net income	636.8					465.7			465.7	171.1
Other comprehensive income:
Currency translation differences on investments in overseas subsidiaries	77.3	[1]						82.6	82.6	(5.3)
Change in accumulated OCI related to employee benefit plans	18.7							18.7	18.7
Change in accumulated OCI of equity method investments	2.9							2.9	2.9
Change in net unrealized gains on available-for-sale investments	9.9							9.9	9.9
Tax impacts of changes in accumulated other comprehensive income balances	(7.0)							(7.0)	(7.0)
Total comprehensive income/(loss)	738.6								572.8	165.8
Net income reclassified to appropriated retained earnings							77.1		77.1	(77.1)
Currency translation differences on investments in overseas subsidiaries reclassified to appropriated retained earnings							(5.3)		(5.3)	5.3
Change in noncontrolling interests in consolidated entities, net	(69.2)									(69.2)
Business Combinations	1,082.2		6.2	563.0			149.4		718.6	363.6
Dividends	(197.9)					(197.9)			(197.9)
Employee share plans:
Share-based compensation	117.8			117.8					117.8
Vested shares				(94.5)	94.5
Exercise of options	19.6			(26.9)	46.5				19.6
Tax impact of share-based payment	14.8			14.8					14.8
Purchase of shares	(240.1)				(240.1)				(240.1)
Ending Balance, value at Dec. 31, 2010	9,360.9		98.1	6,262.6	(991.5)	1,904.4	495.5	495.5	8,264.6	1,096.3
Net income	622.0		0	0	0	729.7	0	0	729.7	(107.7)
Other comprehensive income:
Currency translation differences on investments in overseas subsidiaries	(48.8)	[1]						(71.9)	(71.9)	23.1
Change in accumulated OCI related to employee benefit plans	(42.4)							(42.4)	(42.4)
Change in accumulated OCI of equity method investments	(7.2)							(7.2)	(7.2)
Change in net unrealized gains on available-for-sale investments	(12.3)							(12.3)	(12.3)
Tax impacts of changes in accumulated other comprehensive income balances	11.6							11.6	11.6
Total comprehensive income/(loss)	522.9								607.5	(84.6)
Net income reclassified to appropriated retained earnings							(169.9)		(169.9)	169.9
Currency translation differences on investments in overseas subsidiaries reclassified to appropriated retained earnings							8.7		8.7	(8.7)
Change in noncontrolling interests in consolidated entities, net	(154.4)									(154.4)
Dividends	(220.9)					(220.9)			(220.9)
Employee share plans:
Share-based compensation	115.1			115.1					115.1
Vested shares				(202.7)	202.7
Exercise of options	12.4			(9.1)	21.5				12.4
Tax impact of share-based payment	14.7			14.7					14.7
Purchase of shares	(513.1)				(513.1)				(513.1)
Ending Balance, value at Dec. 31, 2011	$ 9,137.6		$ 98.1	$ 6,180.6	$ (1,280.4)	$ 2,413.2	$ 334.3	$ 373.3	$ 8,119.1	$ 1,018.5

[1] Included in this amount are net gains of $23.1 million for the year ended December 31, 2011 related to foreign currency translation adjustments attributable to consolidated investment products (year ended December 31, 2010: net losses of $5.3 million). Of this amount, $8.7 million is reclassified from accumulated other comprehensive income into retained earnings appropriated for investors in consolidated investment products (year ended December 31, 2010: $5.3 million).