Acquisitions - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		0 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended			0 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Aug. 29, 2014 Autocam [Member]	Sep. 30, 2014 Autocam [Member]	Sep. 30, 2014 Autocam [Member]	Sep. 30, 2014 Autocam [Member]	Sep. 30, 2014 Autocam [Member] Third Quarter [Member]	Sep. 30, 2014 Autocam [Member] First Nine Months [Member]	Sep. 30, 2014 Rfk And Chelsea Grinding [Member] Customer Contracts and Trade Names [Member]	Sep. 30, 2014 Rfk And Chelsea Grinding [Member] Metal Bearing Components Segment [Member]	Jul. 15, 2014 Chelsea Grinding [Member]	Sep. 30, 2014 Chelsea Grinding [Member]	Jun. 20, 2014 RFK [Member]	Sep. 30, 2014 RFK [Member]	Sep. 30, 2014 RFK [Member]	Jan. 30, 2014 VS [Member]	Sep. 30, 2014 VS [Member]
Business Acquisition [Line Items]
Date of acquisition								Aug. 29, 2014						Jul. 15, 2014			Jun. 20, 2014		Jan. 30, 2014
Payments to acquire					$ 256,837								$ 3,100		$ 9,756	$ 2,528
Debt and capital lease obligations					29,160
Business acquisition, consideration transferred in NN stock					31,717
Term loan facility						350,000	350,000	350,000
Business acquisition, transaction costs	8,509		8,933				3,010	3,125	5,316	5,857
Business acquisition, deferred financing costs write off										2,974
Increase in cost of sales									1,992	1,274
Business combinations revenue during period from acquired business						21,639											2,564		10,518
Business combinations net income during period from acquired business	(3,840)	5,052	6,599	12,693		1,382											88		(957)
Payments to Acquire Businesses	20,995		20,995		401,060
Business acquisition, transaction costs	1,179		1,179
Intangible assets subject to amortization					51,098						2,705
Goodwill from acquisition			79,586									2,038
Finite-Lived Intangible Assets, Weighted-Average Useful Life											10 years
Revenue during period from acquired business													500
Percentage of shares acquired															79.20%	99.70%	99.70%
Expected sales of acquired entity	166,979	152,708	505,891	457,466													12,000
Non-controlling interest			(38)														38
Percentage of shares owned by non controlling owners																0.30%	0.30%
Operating assets acquired in cash			259,504															5,580
Liabilities assumed																		$ 2,968