Intangible Assets and Goodwill (Intangibles Subject to Amortization) (Details) - USD ($) $ in Thousands  | 
Sep. 30, 2018  | 
Dec. 31, 2017  | 
|---|---|---|
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying amount | $ 560,749 | |
| Accumulated amortization | (80,190) | |
| Net carrying amount | 480,559 | $ 4,237 | 
| Customer relationships | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying amount | 443,267 | |
| Accumulated amortization | (46,981) | |
| Net carrying amount | 396,286 | |
| Other amortizable intangibles | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying amount | 117,482 | |
| Accumulated amortization | (33,209) | |
| Net carrying amount | $ 84,273 | 
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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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