Acquisitions and Dispositions - Dispositions (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended	9 Months Ended
	Jun. 21, 2017	Sep. 30, 2017	Oct. 01, 2016	Jul. 01, 2017	Sep. 30, 2017	Oct. 01, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net income (loss)		$ (788)	$ 2,244		$ (3,492)	$ 6,097
Gain on sale of business					1,491	0
Mueller-Xingrong [Member] | Disposed of by sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of interest in joint venture	$ 18,300
Assets disposed of	56,700
Liabilities disposed of	36,200
Cumulative translation gain as a result of sale	$ 3,800
Gain on sale of business				$ 1,500
Mueller-Xingrong [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage	50.50%
Net sales					67,300	69,600
Net income (loss)					$ (9)	$ 426