Note 3 - Acquisitions (Detail) (USD $)	3 Months Ended		9 Months Ended				3 Months Ended	9 Months Ended	12 Months Ended			3 Months Ended	9 Months Ended	12 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended			3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011 Accrued [Member] MES Group [Member]	Dec. 31, 2011 Accrued [Member] Other 2011 Acquisitions [Member]	Sep. 30, 2011 MES Group [Member]	Sep. 30, 2011 MES Group [Member]	Dec. 31, 2011 MES Group [Member]	Sep. 30, 2012 MES Group [Member]	Feb. 28, 2011 MES Group [Member]	Sep. 30, 2011 Premex Group [Member]	Sep. 30, 2011 Premex Group [Member]	Dec. 31, 2011 Premex Group [Member]	Sep. 30, 2012 Other 2011 Acquisitions [Member]	Sep. 30, 2012 Other 2011 Acquisitions [Member]	Dec. 31, 2011 Other 2011 Acquisitions [Member]	Dec. 31, 2010 Other 2011 Acquisitions [Member]	Feb. 18, 2011 National IME Centres Inc. [Member]	Sep. 30, 2012 Other 2012 Acquisitions [Member]	Sep. 30, 2012 Other 2012 Acquisitions [Member]	Sep. 30, 2012 Additional Interest Expense [Member]	Sep. 30, 2011 Additional Interest Expense [Member]	Sep. 30, 2012 Additional Interest Expense [Member]	Sep. 30, 2011 Additional Interest Expense [Member]	Sep. 30, 2012 Incremental Depreciation [Member]	Sep. 30, 2011 Incremental Depreciation [Member]	Sep. 30, 2012 Incremental Depreciation [Member]	Sep. 30, 2011 Incremental Depreciation [Member]	Sep. 30, 2012 Selling, General and Administrative Expenses [Member]	Sep. 30, 2011 Selling, General and Administrative Expenses [Member]	Sep. 30, 2012 Selling, General and Administrative Expenses [Member]	Sep. 30, 2011 Selling, General and Administrative Expenses [Member]
Business Acquisition, Percentage of Voting Interests Acquired	100.00%		100.00%						100.00%					100.00%					100.00%
Business Acquisition, Cost of Acquired Entity, Purchase Price									$ 215,000,000					$ 108,400,000			$ 44,600,000			$ 95,886,000	$ 95,886,000
Business Acquisition, Cost of Acquired Entity, Cash Paid									175,000,000					66,500,000			43,200,000			96,900,000	96,900,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares)									1,424,501					661,610			214,926				6,190
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned									30,000,000					15,100,000			2,000,000			85,000	85,000
Closing Price Per Share (in Dollars per share)											$ 21.07			$ 22.85
Business Acquisition, Purchase Price Allocation, Liabilities Assumed											10,000,000			26,800,000
Business Acquisition, Cost of Acquired Entity, Transaction Costs					2,000,000	643,000								646,000			186,000	81,000		1,200,000	1,200,000
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed							8,000	529,000				12,000	655,000		3,000	38,000
Other Intangible Assets Not Expected To Be Deductible For Tax Purposes										54,600,000
Business Acquisition, Purchase Price Allocation, Current Assets, Cash and Cash Equivalents																	564,000			1,100,000	1,100,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred																1,500,000
Business Acquisition, Purchase Price Allocation, Goodwill, Expected Tax Deductible Amount															18,200,000	18,200,000
Business Acquisition Purchase Price Allocation Intangible Assets Expected Tax Deductible Amount															20,800,000	20,800,000
Business Combination, Acquisition Related Costs																				780,000	1,200,000
Revenue, Net	130,085,000	109,218,000	381,600,000	282,548,000																5,500,000
Operating Income (Loss)	1,266,000	1,198,000	3,237,000	4,385,000																108,000
Business Acquisition Proforma Adjustments																						$ 1,100,000	$ 2,800,000	$ 3,900,000	$ 11,400,000	$ 1,600,000	$ 4,000,000	$ 6,600,000	$ 17,400,000	$ 2,000,000	$ 2,400,000	$ 1,500,000	$ 12,600,000