Acquired Intangible Assets and Weighted Average Amortization Periods (Detail) (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
	Mar. 18, 2013	Dec. 31, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total	$ 13,016	$ 24,827	$ 89,921
Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total	1,005	8,973	4,168
Weighted Average Life	15 years	15 years	15 years
Non-Compete Agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total	224	470	793
Weighted Average Life	3 years	3 years	2 years
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total	10,950	11,343	53,895
Weighted Average Life	9 years	6 years	7 years
Unpatented technology and other
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total	837	4,041	28,048
Weighted Average Life	8 years	8 years	6 years
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Total			$ 3,017
Weighted Average Life			10 years