Note 3 - Acquisitions (Detail) - Preliminary Allocation of Purchase Price (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Goodwill	$ 370,143	$ 300,260
Totals	109,200
Preliminary Purchase Price Allocation [Member] | MES Group [Member] | Customer Relationships [Member]
Intangible Assets		38,190
Preliminary Purchase Price Allocation [Member] | MES Group [Member] | Trade Names [Member]
Intangible Assets		17,426
Preliminary Purchase Price Allocation [Member] | MES Group [Member] | Noncompete Agreements [Member]
Intangible Assets		511
Preliminary Purchase Price Allocation [Member] | MES Group [Member] | Unpatented Technology [Member]
Intangible Assets		762
Preliminary Purchase Price Allocation [Member] | MES Group [Member]
Building, equipment and leasehold improvements		1,800
Goodwill		159,988
Net deferred tax liability associated with step-up in book basis		(18,244)
Assets acquired and liabilities assumed, net		14,581
Totals		215,014
Preliminary Purchase Price Allocation [Member] | Premex Group [Member] | Customer Relationships [Member]
Intangible Assets		32,886
Preliminary Purchase Price Allocation [Member] | Premex Group [Member] | Trade Names [Member]
Intangible Assets		10,602
Preliminary Purchase Price Allocation [Member] | Premex Group [Member] | Noncompete Agreements [Member]
Intangible Assets		109
Preliminary Purchase Price Allocation [Member] | Premex Group [Member] | Unpatented Technology [Member]
Intangible Assets		2,356
Preliminary Purchase Price Allocation [Member] | Premex Group [Member]
Building, equipment and leasehold improvements		650
Goodwill		28,131
Net deferred tax liability associated with step-up in book basis		603
Assets acquired and liabilities assumed, net		33,019
Totals		108,356
Preliminary Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Customer Relationships [Member]
Intangible Assets		18,577
Preliminary Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Trade Names [Member]
Intangible Assets		2,989
Preliminary Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Noncompete Agreements [Member]
Intangible Assets		197
Preliminary Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Unpatented Technology [Member]
Intangible Assets		334
Preliminary Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member]
Building, equipment and leasehold improvements		213
Goodwill		21,500
Net deferred tax liability associated with step-up in book basis		(356)
Assets acquired and liabilities assumed, net		2,598
Totals		46,052
Purchase Price Adjustments and Reclassifications [Member] | MES Group [Member]
Goodwill		2,048
Net deferred tax liability associated with step-up in book basis		693
Assets acquired and liabilities assumed, net		(2,741)
Purchase Price Adjustments and Reclassifications [Member] | Premex Group [Member]
Goodwill		3,686
Net deferred tax liability associated with step-up in book basis		(3,695)
Assets acquired and liabilities assumed, net		9
Purchase Price Adjustments and Reclassifications [Member] | Other 2011 Acquisitions [Member]
Goodwill		(1,653)
Net deferred tax liability associated with step-up in book basis		50
Assets acquired and liabilities assumed, net		104
Totals		(1,499)
Final Purchase Price Allocation [Member] | MES Group [Member] | Customer Relationships [Member]
Intangible Assets	38,190
Final Purchase Price Allocation [Member] | MES Group [Member] | Trade Names [Member]
Intangible Assets	17,426
Final Purchase Price Allocation [Member] | MES Group [Member] | Noncompete Agreements [Member]
Intangible Assets	511
Final Purchase Price Allocation [Member] | MES Group [Member] | Unpatented Technology [Member]
Intangible Assets	762
Final Purchase Price Allocation [Member] | MES Group [Member]
Building, equipment and leasehold improvements	1,800
Goodwill	162,036
Net deferred tax liability associated with step-up in book basis	(17,551)
Assets acquired and liabilities assumed, net	11,840
Totals	215,014
Final Purchase Price Allocation [Member] | Premex Group [Member] | Customer Relationships [Member]
Intangible Assets	32,886
Final Purchase Price Allocation [Member] | Premex Group [Member] | Trade Names [Member]
Intangible Assets	10,602
Final Purchase Price Allocation [Member] | Premex Group [Member] | Noncompete Agreements [Member]
Intangible Assets	109
Final Purchase Price Allocation [Member] | Premex Group [Member] | Unpatented Technology [Member]
Intangible Assets	2,356
Final Purchase Price Allocation [Member] | Premex Group [Member]
Building, equipment and leasehold improvements	650
Goodwill	31,817
Net deferred tax liability associated with step-up in book basis	(3,092)
Assets acquired and liabilities assumed, net	33,028
Totals	108,356
Final Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Customer Relationships [Member]
Intangible Assets	18,577
Final Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Trade Names [Member]
Intangible Assets	2,989
Final Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Noncompete Agreements [Member]
Intangible Assets	197
Final Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member] | Unpatented Technology [Member]
Intangible Assets	334
Final Purchase Price Allocation [Member] | Other 2011 Acquisitions [Member]
Building, equipment and leasehold improvements	213
Goodwill	19,847
Net deferred tax liability associated with step-up in book basis	(306)
Assets acquired and liabilities assumed, net	2,702
Totals	44,553
MES Group [Member]
Totals		215,000
Premex Group [Member]
Totals		108,400
Other 2011 Acquisitions [Member]
Totals		$ 43,200