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Summary of Significant Accounting Policies - Narrative (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jan. 01, 2019
Noncontrolling Interest [Line Items]
Temporary investments		$ 600	$ 600
Restricted cash		$ 4,400	$ 6,200
Specified percentage over which unrecognized gains and losses are amortized		10.00%
Average remaining service period for the pension plans		9 years
Stock-based awards excluded from the computation of diluted earnings per share (in shares)		54	20
Foreign currency transaction gains (losses)		$ (1,000)	$ (400)	$ 400
Net periodic benefit (income) cost		(2,914)	(1,150)	1,687
Future minimum lease payments under operating lease		$ 38,300	40,500
Tecumseh Products Holdings LLC [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		50.00%
Second Unconsolidated Affiliate [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		50.00%
Mueller Middle East BSC [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		40.00%
Building [Member] \| Minimum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		20 years
Building [Member] \| Maximum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		40 years
Machinery and Equipment [Member] \| Minimum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		5 years
Machinery and Equipment [Member] \| Maximum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		20 years
Mueller-Xingrong [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest		49.50%
Jungwoo-Mueller [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest		40.00%
Other Nonoperating Income (Expense) [Member]
Noncontrolling Interest [Line Items]
Net periodic benefit (income) cost			(1,200)	(1,700)
Accounting Standards Update 2018-02 [Member]
Noncontrolling Interest [Line Items]
Reclassification of stranded effects of the Act	$ 556
Accounting Standards Update 2017-07 [Member] \| Operating Income (Loss) [Member]
Noncontrolling Interest [Line Items]
Net periodic benefit (income) cost			(1,200)	1,700
Accounting Standards Update 2016-18 [Member]
Noncontrolling Interest [Line Items]
Increase in cash, cash equivalents and restricted cash			$ 6,300	$ 9,200
Subsequent Event [Member] \| Scenario, Forecast [Member] \| Accounting Standards Update 2018-10 [Member] \| Minimum [Member]
Noncontrolling Interest [Line Items]
Right-of-Use asset					$ 25,000
Lease liability					25,000
Subsequent Event [Member] \| Scenario, Forecast [Member] \| Accounting Standards Update 2018-10 [Member] \| Maximum [Member]
Noncontrolling Interest [Line Items]
Right-of-Use asset					35,000
Lease liability					$ 30,000