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Acquisitions and Dispositions - Acquisition (Details) - USD ($) $ in Thousands |  |  |  |  |  | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
May 31, 2017 | Apr. 26, 2016 | Jul. 31, 2015 | Jun. 18, 2015 | Mar. 30, 2015 | Dec. 30, 2017 | Dec. 31, 2016 | Dec. 26, 2015 | Feb. 28, 2014
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition |  |  |  |  |  | $ 18,396 | $ 20,533 | $ 105,944 |
Allocated to: |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  | 130,293 | 123,993 | $ 120,252 |
Noncontrolling interests |  |  |  |  |  | $ 13,917 | $ 37,753 |  |
Customer Relationships [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 20 years |  |  |
Non-compete Agreements [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 3 years |  |  |
Non-compete Agreements [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 5 years |  |  |
Patents and Technology [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 10 years |  |  |
Patents and Technology [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 15 years |  |  |
Trade names and licenses [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 5 years |  |  |
Trade names and licenses [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Intangible asset type: |  |  |  |  |  |  |  |  |
Estimated Useful Life |  |  |  |  |  | 10 years |  |  |
Pexcor/Heatlink [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition | $ 16,300 |  |  |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract] |  |  |  |  |  |  |  |  |
Total consideration | 16,317 |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Accounts receivable | 2,809 |  |  |  |  |  |  |  |
Inventories | 4,648 |  |  |  |  |  |  |  |
Other current assets | 508 |  |  |  |  |  |  |  |
Property, plant, and equipment | 2,024 |  |  |  |  |  |  |  |
Goodwill | 4,071 |  |  |  |  |  |  |  |
Intangible assets | 6,413 | $ 6,413 |  |  |  |  |  |  |
Other assets | 0 |  |  |  |  |  |  |  |
Total assets acquired | 20,473 |  |  |  |  |  |  |  |
Accounts payable | 3,633 |  |  |  |  |  |  |  |
Accrued wages & other employee costs | 0 |  |  |  |  |  |  |  |
Other current liabilities | 523 |  |  |  |  |  |  |  |
Long-term debt | 0 |  |  |  |  |  |  |  |
Pension and other postretirement liabilities | 0 |  |  |  |  |  |  |  |
Other noncurrent liabilities | 0 |  |  |  |  |  |  |  |
Total liabilities assumed | 4,156 |  |  |  |  |  |  |  |
Noncontrolling interests | 0 |  |  |  |  |  |  |  |
Net assets acquired | $ 16,317 |  |  |  |  |  |  |  |
Pexcor/Heatlink [Member] | Customer Relationships [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  | 4,265 |  |  |  |  |  |  |
Pexcor/Heatlink [Member] | Non-compete Agreements [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  | 74 |  |  |  |  |  |  |
Pexcor/Heatlink [Member] | Patents and Technology [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  | 1,466 |  |  |  |  |  |  |
Pexcor/Heatlink [Member] | Trade names and licenses [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  | 608 |  |  |  |  |  |  |
Jungwoo-Mueller [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition |  | $ 20,500 |  |  |  |  |  |  |
Equity method investment, ownership percentage |  | 60.00% |  |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract] |  |  |  |  |  |  |  |  |
Total consideration |  | $ 20,533 |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Accounts receivable |  | 5,551 |  |  |  |  |  |  |
Inventories |  | 17,616 |  |  |  |  |  |  |
Other current assets |  | 1,437 |  |  |  |  |  |  |
Property, plant, and equipment |  | 24,191 |  |  |  |  |  |  |
Goodwill |  | 223 |  |  |  |  |  |  |
Intangible assets |  | 756 | $ 756 |  |  |  |  |  |
Other assets |  | 277 |  |  |  |  |  |  |
Total assets acquired |  | 50,051 |  |  |  |  |  |  |
Accounts payable |  | 7,252 |  |  |  |  |  |  |
Accrued wages & other employee costs |  | 0 |  |  |  |  |  |  |
Other current liabilities |  | 577 |  |  |  |  |  |  |
Long-term debt |  | 8,659 |  |  |  |  |  |  |
Pension and other postretirement liabilities |  | 799 |  |  |  |  |  |  |
Other noncurrent liabilities |  | 582 |  |  |  |  |  |  |
Total liabilities assumed |  | 17,869 |  |  |  |  |  |  |
Noncontrolling interests |  | 11,649 |  |  |  |  |  |  |
Net assets acquired |  | $ 20,533 |  |  |  |  |  |  |
Jungwoo-Mueller [Member] | Customer Relationships [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 0 |  |  |  |  |  |
Jungwoo-Mueller [Member] | Non-compete Agreements [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 0 |  |  |  |  |  |
Jungwoo-Mueller [Member] | Patents and Technology [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 756 |  |  |  |  |  |
Jungwoo-Mueller [Member] | Trade names and licenses [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 0 |  |  |  |  |  |
Great Lakes Copper, Inc [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition |  |  | 70,000 |  |  |  |  |  |
Cost of acquisition, post-closing working capital adjustment |  |  | 1,500 |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract] |  |  |  |  |  |  |  |  |
Total consideration |  |  | 70,011 |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Accounts receivable |  |  | 26,079 |  |  |  |  |  |
Inventories |  |  | 15,233 |  |  |  |  |  |
Other current assets |  |  | 22 |  |  |  |  |  |
Property, plant, and equipment |  |  | 22,771 |  |  |  |  |  |
Goodwill |  |  | 23,208 |  |  |  |  |  |
Intangible assets |  |  | 27,468 |  | $ 27,468 |  |  |  |
Other assets |  |  | 1,413 |  |  |  |  |  |
Total assets acquired |  |  | 116,194 |  |  |  |  |  |
Accounts payable |  |  | 36,026 |  |  |  |  |  |
Accrued wages & other employee costs |  |  | 0 |  |  |  |  |  |
Other current liabilities |  |  | 381 |  |  |  |  |  |
Long-term debt |  |  | 0 |  |  |  |  |  |
Pension and other postretirement liabilities |  |  | 5,655 |  |  |  |  |  |
Other noncurrent liabilities |  |  | 4,121 |  |  |  |  |  |
Total liabilities assumed |  |  | 46,183 |  |  |  |  |  |
Noncontrolling interests |  |  | 0 |  |  |  |  |  |
Net assets acquired |  |  | $ 70,011 |  |  |  |  |  |
Great Lakes Copper, Inc [Member] | Customer Relationships [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 20,273 |  |  |  |
Great Lakes Copper, Inc [Member] | Non-compete Agreements [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 2,269 |  |  |  |
Great Lakes Copper, Inc [Member] | Patents and Technology [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 3,104 |  |  |  |
Great Lakes Copper, Inc [Member] | Trade names and licenses [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 1,822 |  |  |  |
Sherwood Valve Products, LLC [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition |  |  |  | $ 21,800 |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract] |  |  |  |  |  |  |  |  |
Total consideration |  |  |  | 21,795 |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Accounts receivable |  |  |  | 6,490 |  |  |  |  |
Inventories |  |  |  | 11,892 |  |  |  |  |
Other current assets |  |  |  | 260 |  |  |  |  |
Property, plant, and equipment |  |  |  | 10,327 |  |  |  |  |
Goodwill |  |  |  | 0 |  |  |  |  |
Intangible assets |  |  |  | (38) |  |  |  |  |
Other assets |  |  |  | 0 |  |  |  |  |
Total assets acquired |  |  |  | 28,931 |  |  |  |  |
Accounts payable |  |  |  | 6,022 |  |  |  |  |
Accrued wages & other employee costs |  |  |  | 471 |  |  |  |  |
Other current liabilities |  |  |  | 487 |  |  |  |  |
Long-term debt |  |  |  | 0 |  |  |  |  |
Pension and other postretirement liabilities |  |  |  | 0 |  |  |  |  |
Other noncurrent liabilities |  |  |  | 156 |  |  |  |  |
Total liabilities assumed |  |  |  | 7,136 |  |  |  |  |
Noncontrolling interests |  |  |  | 0 |  |  |  |  |
Net assets acquired |  |  |  | $ 21,795 |  |  |  |  |
Turbotec Products, Inc. [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Cash paid for acquisition |  |  |  |  | 14,100 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract] |  |  |  |  |  |  |  |  |
Total consideration |  |  |  |  | 14,138 |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Accounts receivable |  |  |  |  | 1,936 |  |  |  |
Inventories |  |  |  |  | 3,247 |  |  |  |
Other current assets |  |  |  |  | 72 |  |  |  |
Property, plant, and equipment |  |  |  |  | 9,080 |  |  |  |
Goodwill |  |  |  |  | 2,088 |  |  |  |
Intangible assets |  |  |  |  | 880 |  |  |  | $ 880
Other assets |  |  |  |  | 59 |  |  |  |
Total assets acquired |  |  |  |  | 17,362 |  |  |  |
Accounts payable |  |  |  |  | 1,603 |  |  |  |
Accrued wages & other employee costs |  |  |  |  | 356 |  |  |  |
Other current liabilities |  |  |  |  | 51 |  |  |  |
Long-term debt |  |  |  |  | 0 |  |  |  |
Pension and other postretirement liabilities |  |  |  |  | 0 |  |  |  |
Other noncurrent liabilities |  |  |  |  | 1,214 |  |  |  |
Total liabilities assumed |  |  |  |  | 3,224 |  |  |  |
Noncontrolling interests |  |  |  |  | 0 |  |  |  |
Net assets acquired |  |  |  |  | $ 14,138 |  |  |  |
Turbotec Products, Inc. [Member] | Customer Relationships [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  |  |  |  |  | 350
Turbotec Products, Inc. [Member] | Non-compete Agreements [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  |  |  |  |  | 90
Turbotec Products, Inc. [Member] | Patents and Technology [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  |  |  |  |  | 220
Turbotec Products, Inc. [Member] | Trade names and licenses [Member] |  |  |  |  |  |  |  |  |
Allocated to: |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  |  |  |  |  | $ 220

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