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Represents the unrecognized gains and losses which are amortized when the net gains and losses exceed specified percent of the greater of the market value of the plan assets or the projected benefit obligation.

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Temporary investments with original maturities of less than three months.

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No definition available.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

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Amount of lessee's right to use underlying asset under operating lease.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Summary of Significant Accounting Policies (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017	Jan. 01, 2019
Noncontrolling Interest [Line Items]
Temporary investments	$ 500	$ 600
Operating lease renewal term	5 years
Weighted average remaining lease term (in years)	8 years 4 months 6 days
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)	0	54
Foreign currency transaction gains (losses)	$ 200	$ (1,000)	$ (400)
Operating lease right-of-use assets	26,922			$ 29,500
Current portion of operating lease liabilities	5,250			4,800
Noncurrent operating lease liabilities	$ 22,388			$ 25,400
Minimum [Member]
Noncontrolling Interest [Line Items]
Weighted average remaining lease term (in years)	1 year
Maximum [Member]
Noncontrolling Interest [Line Items]
Weighted average remaining lease term (in years)	15 years
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
Jungwoo Metal Ind. Co., LTD [Member] \| Jungwoo-Mueller [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest	40.00%
Mueller-Xingrong [Member] \| Mueller-Xingrong [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest	49.50%