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Goodwill and Identifiable Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Apr. 02, 2018 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Intangible Assets [Line Items] |  |  |  |  |  |
Amortization of intangible assets |  | $ 18,540 | $ 8,248 | $ 44,689 | $ 25,011 |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 483,462 |  | 483,462 |  | $ 305,359
Accumulated Amortization |  | 243,173 |  | 243,173 |  | 198,535
Net Carrying Amount |  | 240,289 |  | 240,289 |  | 106,824
Intangible assets not subject to amortization: |  |  |  |  |  |
Trademarks, Carrying Amount |  | 262,268 |  | 262,268 |  | 245,942
Goodwill, Carrying Amount | $ 527,388 | 1,420,636 |  | 1,420,636 |  | 894,095
Intangible Assets, Gross (Excluding Goodwill) |  | 745,730 |  | 745,730 |  | 551,301
Total |  |  |  |  |  |
Intangible Assets, Net (Excluding Goodwill) |  | 502,557 |  | 502,557 |  | 352,766
Customer Contractual Relationships |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life | 13 years |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 343,707 |  | 343,707 |  | 202,588
Accumulated Amortization |  | 135,739 |  | 135,739 |  | 119,272
Net Carrying Amount |  | 207,968 |  | $ 207,968 |  | 83,316
Customer Contractual Relationships | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 2 years |  |
Customer Contractual Relationships | Maximum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 13 years |  |
Contractor Relations [Member] |  |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 71,121 |  | $ 71,121 |  | 71,121
Accumulated Amortization |  | 65,102 |  | 65,102 |  | 59,174
Net Carrying Amount |  | 6,019 |  | $ 6,019 |  | 11,947
Contractor Relations [Member] | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 2 years |  |
Contractor Relations [Member] | Maximum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 5 years |  |
Backlog [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life | 1 year |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 26,100 |  | $ 26,100 |  | 0
Accumulated Amortization |  | 17,400 |  | 17,400 |  | 0
Net Carrying Amount |  | 8,700 |  | $ 8,700 |  | 0
Backlog [Member] | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 1 year |  |
Non-compete agreements |  |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 22,234 |  | $ 22,234 |  | 11,850
Accumulated Amortization |  | 8,950 |  | 8,950 |  | 6,600
Net Carrying Amount |  | 13,284 |  | $ 13,284 |  | 5,250
Non-compete agreements | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life | 4 years |  |  | 2 years |  |
Non-compete agreements | Maximum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life | 7 years |  |  | 7 years |  |
Favorable Contracts [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life | 5 years |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 1,400 |  | $ 1,400 |  | 900
Accumulated Amortization |  | 804 |  | 804 |  | 673
Net Carrying Amount |  | 596 |  | $ 596 |  | 227
Favorable Contracts [Member] | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 5 years |  |
Computer Software, Intangible Asset [Member] |  |  |  |  |  |
Intangible assets subject to amortization: |  |  |  |  |  |
Gross Carrying Amount |  | 18,900 |  | $ 18,900 |  | 18,900
Accumulated Amortization |  | 15,178 |  | 15,178 |  | 12,816
Net Carrying Amount |  | $ 3,722 |  | $ 3,722 |  | $ 6,084
Computer Software, Intangible Asset [Member] | Minimum [Member] |  |  |  |  |  |
Intangible Assets [Line Items] |  |  |  |  |  |
Estimated Useful Life |  |  |  | 6 years |  |

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