Annual report pursuant to Section 13 and 15(d)

Acquisitions, Goodwill and Other Long-Lived Assets Estimated Amortization Expense (Details)

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Acquisitions, Goodwill and Other Long-Lived Assets Estimated Amortization Expense (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Intangible Assets [Line Items]    
Finite-lived Intangible Assets Acquired $ 199,275 $ 184,485
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]    
Year 2018 8,896  
Year 2019 8,608  
Year 2020 8,578  
Year 2021 8,423  
Year 2022 8,054  
Finite-Lived Intangible Assets, Accumulated Amortization 71,527 61,334
Impairment of Intangible Assets, Finite-lived 16,501 16,501
Intangible Assets, Net (Excluding Goodwill) 111,247 106,650
Customer Relationships [Member]    
Intangible Assets [Line Items]    
Finite-lived Intangible Assets Acquired 193,209 179,575
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]    
Year 2018 8,399  
Year 2019 8,319  
Year 2020 8,319  
Year 2021 8,177  
Year 2022 $ 7,976  
Finite-Lived Intangible Asset, Useful Life 15 years 10 months 11 days  
Finite-Lived Intangible Assets, Accumulated Amortization $ 66,986 57,390
Impairment of Intangible Assets, Finite-lived 16,501 16,501
Intangible Assets, Net (Excluding Goodwill) 109,722 105,684
Noncompete Agreements [Member]    
Intangible Assets [Line Items]    
Finite-lived Intangible Assets Acquired 4,566 3,410
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]    
Year 2018 464  
Year 2019 289  
Year 2020 259  
Year 2021 246  
Year 2022 $ 78  
Finite-Lived Intangible Asset, Useful Life 5 years 2 months 11 days  
Finite-Lived Intangible Assets, Accumulated Amortization $ 3,074 2,677
Intangible Assets, Net (Excluding Goodwill) 1,492 733
Trade Names [Member]    
Intangible Assets [Line Items]    
Finite-lived Intangible Assets Acquired 1,500 1,500
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]    
Year 2018 33  
Year 2019 0  
Year 2020 0  
Year 2021 0  
Year 2022 $ 0  
Finite-Lived Intangible Asset, Useful Life 4 years 11 days  
Finite-Lived Intangible Assets, Accumulated Amortization $ 1,467 1,267
Intangible Assets, Net (Excluding Goodwill) $ 33 $ 233