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Acquisitions (Narrative) (Details) - USD ($) $ in Thousands |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jun. 09, 2015 | Sep. 30, 2013 | Mar. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Business Acquisition [Line Items] |  |  |  |  |  |
Remaining purchase adjustment |  |  |  | $ 2,314 |  |
Goodwill |  |  |  | 292,390 | $ 236,044 | $ 341,174
Rough Brothers Incorporated |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Acquisition purchase price | $ 147,585 |  |  |  |  |
Working capital adjustment | 6,302 |  |  |  |  |
Goodwill | 57,180 |  |  |  |  |
Tax deductible goodwill | 37,969 |  |  |  |  |
Indemnification assets | 3,000 |  |  |  |  |
Fair value of purchase consideration | $ 147,585 |  |  |  |  |
2013 Acquisitions |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Goodwill |  |  |  |  | 2,466 |
Fair value of purchase consideration |  | $ 7,454 |  |  | 7,454 |
Payment for aggregate purchase consideration |  | $ 2,322 |  | 61 | 368 |
2013 Acquisitions | SG&A |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Adjustment to payable, expense recorded |  |  |  | (480) | (1,611) |
2013 Acquisitions | Interest Expense |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Adjustment to payable, expense recorded |  |  |  | $ 8 | $ 75 |
2013 Acquisitions | Interest Expense | Forecast |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Final remittance payment |  |  | $ 61 |  |  |

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