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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

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