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Segment Information (Details) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 USD ($) | Jun. 30, 2017 USD ($) | Jun. 30, 2018 USD ($) segment | Jun. 30, 2017 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Number of reportable segments | segment |  |  | 3 |
Net sales: | $ 266,036 | $ 247,627 | $ 481,373 | $ 454,232
Income from operations: | 70,503 | 61,825 | 118,821 | 111,080
Unallocated Corporate Expenses | (8,082) | (4,538) | (14,141) | (13,803)
Total income from operations | 32,274 | 24,930 | 46,117 | 34,609
Residential Products |  |  |  |
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Net sales: | 131,128 | 127,252 | 235,076 | 231,803
Income from operations: | 24,196 | 22,579 | 37,434 | 38,220
Industrial and Infrastructure Products |  |  |  |
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Net sales: | 61,193 | 57,612 | 115,596 | 107,874
Income from operations: | 6,604 | 3,397 | 9,206 | 3,360
Renewable Energy & Conservation |  |  |  |
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Net sales: | 73,715 | 62,763 | 130,701 | 114,555
Income from operations: | 9,556 | 3,492 | 13,618 | 6,832
Intersegment Elimination |  |  |  |
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Net sales: | (368) | (314) | (589) | (770)
Intersegment Elimination | Industrial and Infrastructure Products |  |  |  |
Segment Reporting, Other Significant Reconciling Item [Line Items] |  |  |  |
Net sales: | $ 61,561 | $ 57,926 | $ 116,185 | $ 108,644

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