Acquisitions - Summary of Final Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands			12 Months Ended
	Oct. 02, 2017	Oct. 19, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Consideration:
Property, plant and equipment				$ 58,100	$ 14,000
Intangible assets subject to amortization					6,900
Goodwill			$ 443,529	448,399	454,612
NN Life Sciences Vandalia LLC [Member]
Consideration:
Cash paid	$ 38,700
Current assets	10,166				10,166
Property, plant and equipment	13,981				13,981
Intangible assets subject to amortization	6,900				6,900
Other non-current assets	29				29
Goodwill	9,452				9,452
Total assets acquired	40,528
Current liabilities	1,794
Total liabilities assumed	1,794				1,794
Net assets acquired	$ 38,734				$ 38,734
Precision Engineered Products Group [Member]
Consideration:
Cash paid			621,196	621,196
Cash adjustment			(1,635)
Total consideration			619,561	621,196
Current assets			69,783	69,331
Property, plant and equipment			55,201	56,163
Intangible assets subject to amortization			240,490	240,490
Other non-current assets			1,500	1,500
Goodwill			370,904	372,709
Total assets acquired			737,878	740,193
Current liabilities			21,354	21,354
Non-current deferred tax liabilities			94,755	95,435
Other non-current liabilities			2,208	2,208
Total liabilities assumed			118,317	118,997
Net assets acquired			$ 619,561	$ 621,196
Precision Engineered Products Group [Member] | Subsequent Adjustments to Fair Value [Member]
Consideration:
Cash adjustment		$ (1,635)
Total consideration		(1,635)
Current assets		452
Property, plant and equipment		(962)
Goodwill		(1,805)
Total assets acquired		(2,315)
Non-current deferred tax liabilities		(680)
Total liabilities assumed		(680)
Net assets acquired		$ (1,635)