Acquired Intangible Assets and Related Amortization (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, net	$ 233.3	$ 253.6
Client relationships
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	218.2	217.9
Accumulated amortization	(69.1)	(58.6)
Acquired intangible assets, net	149.1	159.3
Trade secrets
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	31.4	31.3
Accumulated amortization	(15.4)	(13.4)
Acquired intangible assets, net	16.0	17.9
Software
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	72.3	70.9
Accumulated amortization	(31.3)	(25.1)
Acquired intangible assets, net	41.0	45.8
Trade names
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	28.3	28.1
Accumulated amortization	(10.0)	(9.0)
Acquired intangible assets, net	18.3	19.1
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	24.9	24.6
Accumulated amortization	(16.0)	(13.1)
Acquired intangible assets, net	$ 8.9	$ 11.5