Goodwill and Acquired Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009
Goodwill [Roll Forward]
Balance, beginning of period	$ 53,011,000	$ 45,001,000
Goodwill acquired during the period	179,910,000	8,170,000
Foreign currency translation	11,000	(160,000)
Balance, end of period	232,932,000	53,011,000	45,001,000
Intangible Assets [Abstract]
Gross carrying amount	79,076,000	17,733,000
Accumulated amortization	5,663,000	2,994,000
Net carrying amount	73,413,000	14,739,000
Weighted average amortization period (in years)	7.4	7.0
Amortization expense of intangible assets	2,700,000	1,700,000	1,300,000
Future amortization expense of intangible assets [Abstract]
For the year ended 12/31/12	10,239,000
For the year ended 12/31/13	10,047,000
For the year ended 12/31/14	9,439,000
For the year ended 12/31/15	9,402,000
For the year ended 12/31/16	9,311,000
Thereafter	24,975,000
Oil Field [Member]
Goodwill [Roll Forward]
Balance, beginning of period	45,862,000	38,018,000
Goodwill acquired during the period	179,910,000	7,839,000
Foreign currency translation	(2,000)	5,000
Balance, end of period	225,770,000	45,862,000
Power Transmission [Member]
Goodwill [Roll Forward]
Balance, beginning of period	7,149,000	6,983,000
Goodwill acquired during the period	0	331,000
Foreign currency translation	13,000	(165,000)
Balance, end of period	7,162,000	7,149,000
Non-compete agreements and trademarks [Member]
Intangible Assets [Abstract]
Gross carrying amount	6,258,000	2,550,000
Accumulated amortization	1,091,000	619,000
Net carrying amount	5,167,000	1,931,000
Weighted average amortization period (in years)	5.1	6.3
Customer relationships and contracts [Member]
Intangible Assets [Abstract]
Gross carrying amount	72,818,000	15,183,000
Accumulated amortization	4,572,000	2,375,000
Net carrying amount	$ 68,246,000	$ 12,808,000
Weighted average amortization period (in years)	9.6	10.0