Acquisitions (Details) (USD $)		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011 Quinns Oilfield Supply Ltd [Member]	Sep. 30, 2012 Datac Instrumentation Limited [Member]	Jan. 19, 2012 Datac Instrumentation Limited [Member]	Feb. 29, 2012 Zenith Oilfield Technology Ltd [Member]
Business Acquisition [Line Items]
Business acquisition, date of purchase				Jan. 19, 2012	Feb. 29, 2012
Cash paid at closing, net				$ 18,586,000	$ 133,972,000
Common stock paid at closing				8,414,000
Total consideration paid				27,000,000	133,972,000
Restricted shares issued in business acquisition (in shares)			116,716
Business acquisition equity interests issued fair value per share (in dollars per share)				$ 72.09
Purchase price				27,000,000	133,972,000
Receivables				323,000	13,236,000
Inventories				449,000	4,226,000
Other current assets				82,000	7,711,000
Property, plant and equipment				51,000	518,000
Non-compete agreements and trademarks				350,000	3,614,000
Customer relationship and contracts				5,983,000	32,665,000
Other long term assets					355,000
Indemnification asset				5,500,000
Accounts payable				(136,000)	(3,698,000)
Other accrued liabilities				(484,000)	(2,554,000)
Uncertain tax liability				(5,500,000)
Goodwill recorded				20,382,000	77,899,000
Escrow account balance	5,500,000		5,500,000
Pro forma information as if quinn acquisition occurred at beginning of year [Abstract]
Sales		802,967,000
Net earnings		$ 56,701,000
Diluted earnings per share from continuing operations (in dollars per share)		$ 1.68