Segment Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Sales by segment [Abstract]
Gross sales	$ 288,226	$ 197,802
Inter-segment sales	(8,690)	(3,405)
Net sales	279,536	194,397
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	23,994	19,453
Other (expense) income, net	(3,768)	(76)
Earnings (loss) before income tax provision	20,226	19,377
Oil Field [Member]
Sales by segment [Abstract]
Gross sales	240,290	155,183
Inter-segment sales	(4,283)	(1,461)
Net sales	236,007	153,722
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	22,473	17,194
Other (expense) income, net	(3,178)	41
Earnings (loss) before income tax provision	19,295	17,235
Power Transmission [Member]
Sales by segment [Abstract]
Gross sales	47,936	42,619
Inter-segment sales	(4,407)	(1,944)
Net sales	43,529	40,675
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	1,521	2,259
Other (expense) income, net	(14)	(11)
Earnings (loss) before income tax provision	1,507	2,248
Corporate & Other [Member]
Sales by segment [Abstract]
Gross sales	0	0
Inter-segment sales	0	0
Net sales	0	0
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	0	0
Other (expense) income, net	(576)	(106)
Earnings (loss) before income tax provision	$ (576)	$ (106)

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 10

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- Definition

The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

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No definition available.

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Topic 225

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Amount of revenue from transactions with other operating segments of the same entity.

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Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-Section 50

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