Business Acquisitions - Narrative (Details) (USD $) In Thousands, unless otherwise specified		12 Months Ended						12 Months Ended							12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012 TQM [Member]	Dec. 31, 2011 TQM [Member]	Dec. 31, 2011 TQM [Member] Customer Lists [Member]	Dec. 31, 2011 TQM [Member] Trade Names [Member]	Dec. 31, 2012 GW Smith [Member]	Dec. 31, 2011 GW Smith [Member]	Dec. 31, 2011 GW Smith [Member] Customer Lists [Member]	Dec. 31, 2011 GW Smith [Member] Noncompete Agreements [Member]	Dec. 31, 2011 GW Smith [Member] Trademarks [Member]	Dec. 31, 2011 GW Smith [Member] Trade Names [Member]	Dec. 31, 2012 Summit [Member]	Dec. 31, 2011 Summit [Member]	Dec. 31, 2010 Summit [Member]	Dec. 31, 2010 Summit [Member] Customer Lists [Member]	Dec. 31, 2010 Summit [Member] Noncompete Agreements [Member]	Dec. 31, 2010 Summit [Member] Other Intangible Assets [Member]	Dec. 31, 2012 NPCoil Dexter [Member]	Dec. 31, 2012 NPCoil Dexter [Member] Customer Lists [Member]	Dec. 31, 2012 NPCoil Dexter [Member] Customer Relationships [Member]	Dec. 31, 2012 NPCoil Dexter [Member] Noncompete Agreements [Member]	Dec. 31, 2012 NPCoil Dexter [Member] Trademarks [Member]
Business Acquisition [Line Items]
Cash Paid for Acquisition	$ 25,018		$ 10,500				$ 14,518							$ 29,116				$ 2,748
Short-term Debt																		(1,186)
Long-term Debt																		(854)
Goodwill	7,893		6,773				1,120							3,423				1,786
Intangibles	9,816		3,556				6,260							17,100				3,825
Intangible Assets, Amortizable Life				20 years	5 years			16 years	5 years	5 years	15 years				20 years	5 years	15 years		8 years	4 years	5 years	10 years
Percentage of Voting Interests Acquired			60.00%
Post Closing Adjustment													717
Contingent Consideration Paid		2,000				1,000
Gain on Revaluation of Existing Equity Interest in Step Purchase			2,718
Cash Acquired			236				22											113
Change in Fair Value Estimate												$ 1,737	$ 595					$ 1,033