Goodwill and Other Intangible Assets, Net - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense	$ 5,500,000	$ 3,200,000	$ 3,000,000
Expected amortization expense in 2012	4,800,000
Expected amortization expense in 2013	4,100,000
Expected amortization expense in 2014	4,100,000
Expected amortization expense in 2015	4,100,000
Expected amortization expense in 2016	4,100,000
Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Definite-lived intangibles, weighted-average useful life (in years)	18.9
Acquired definite-lived intangibles	28,200,000
Other definite-lived intangibles
Goodwill and Intangible Assets Disclosure [Line Items]
Definite-lived intangibles, weighted-average useful life (in years)	7.2
Trade names
Goodwill and Intangible Assets Disclosure [Line Items]
Acquired definite-lived intangibles	$ 3,400,000