Fair Value - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Fair Value of Financial Instruments [Line Items]
Contingent consideration obligations outstanding	$ 0.1
Contingent consideration at fair value	9.0	[1]	9.1	[1]
Business acquisition contingent consideration obligations, accounts payable and accrued liabilities	2.5
Business acquisition contingent consideration obligations, other liabilities	$ 6.5

[1] Represents contingent consideration liabilities pursuant to the agreements for certain MA acquisitions which are more fully discussed in Note 7.