CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Revenue	$ 551.6	$ 467.3	$ 1,594.8	$ 1,314.5
Operating expenses:
Compensation and related expenses	229.8	196.8	679.7	565.9
Selling, general and administrative	106.4	93.9	298.2	267.7
Intangible amortization and impairments	32.7	24.0	98.1	169.1
Depreciation and other amortization	3.4	3.5	10.3	10.6
Other operating expenses	10.2	9.4	27.5	27.7
Total operating expenses	382.5	327.6	1,113.8	1,041.0
Operating income	169.1	139.7	481.0	273.5
Income from equity method investments	34.1	19.4	121.0	47.3
Other non-operating (income) and expenses:
Investment and other income	(8.0)	(6.9)	(20.0)	(20.3)
Interest expense	19.9	21.8	68.5	58.8
Imputed interest and contingent payment arrangements	3.9	6.7	26.5	(35.7)
Total non-operating (income) and expenses	15.8	21.6	75.0	2.8
Income before income taxes	187.4	137.5	527.0	318.0
Income taxes	31.0	19.4	106.6	46.0
Net income	156.4	118.1	420.4	272.0
Net income (non-controlling interests)	(81.2)	(63.2)	(218.1)	(173.1)
Net income (controlling interest)	$ 75.2	$ 54.9	$ 202.3	$ 98.9
Average shares outstanding - basic (in shares)	53.2	51.7	53.0	51.6
Average shares outstanding-diluted (in shares)	56.9	53.0	54.7	52.9
Earnings per share-basic (in dollars per share)	$ 1.41	$ 1.06	$ 3.82	$ 1.92
Earnings per share-diluted (in dollars per share)	$ 1.37	$ 1.04	$ 3.70	$ 1.87