Acquired Intangible Assets and Weighted Average Amortization Periods (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Total	$ 13,016
Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Total	1,005
Weighted Average Life	15 years
Non-Compete Agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Total	224
Weighted Average Life	3 years
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Total	10,950
Weighted Average Life	9 years
Unpatented technology
Acquired Finite-Lived Intangible Assets [Line Items]
Total	$ 837
Weighted Average Life	8 years