Segment Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Data [Abstract]
Number Of Operating Segments			2
Sales by segment [Abstract]
Gross sales	$ 342,438	$ 236,412	$ 939,216	$ 666,000
Inter-segment sales	(2,093)	(4,698)	(13,690)	(13,130)
Net sales	340,345	231,714	925,526	652,870
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	42,285	23,965	100,134	72,435
Other (expense) income, net	(3,328)	(150)	(10,500)	(415)
Earnings (loss) before income tax provision	38,957	23,815	89,634	72,020
OilField [Member]
Sales by segment [Abstract]
Gross sales	291,200	184,857	785,801	520,776
Inter-segment sales	(1,273)	(1,352)	(6,563)	(4,627)
Net sales	289,927	183,505	779,238	516,149
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	43,430	21,011	97,687	63,136
Other (expense) income, net	(3,514)	(11)	(9,840)	(148)
Earnings (loss) before income tax provision	39,916	21,000	87,847	62,988
Power Transmission [Member]
Sales by segment [Abstract]
Gross sales	51,238	51,555	153,415	145,224
Inter-segment sales	(820)	(3,346)	(7,127)	(8,503)
Net sales	50,418	48,209	146,288	136,721
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	(1,145)	2,954	2,447	9,299
Other (expense) income, net	15	21	54	43
Earnings (loss) before income tax provision	(1,130)	2,975	2,501	9,342
Corporate & Other [Member]
Sales by segment [Abstract]
Gross sales	0	0	0	0
Inter-segment sales	0	0	0	0
Net sales	0	0	0	0
Earnings (loss) before income taxes [Abstract]
Operating income (loss)	0	0	0	0
Other (expense) income, net	171	(160)	(714)	(310)
Earnings (loss) before income tax provision	$ 171	$ (160)	$ (714)	$ (310)