Summary of Significant Accounting Policies - Goodwill (Details) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
|
Mar. 31, 2019
USD ($)
division
|
Dec. 31, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
|
|
| Goodwill And Intangible Assets [Line Items] | |||
| Number of internal divisions | division | 2 | ||
| Decrease in fair value of reporting units considered for impairment calculation | 10.00% | ||
| Goodwill | $ 1,927,028 | $ 1,899,879 | $ 1,868,600 |
| Intangible assets | 276,070 | $ 280,180 | |
| Oil and Gas Infrastructure Services Division | |||
| Goodwill And Intangible Assets [Line Items] | |||
| Goodwill | 48,500 | ||
| Intangible assets | $ 10,700 |
| X | ||||||||||
- Definition Decrease in fair value of Reporting units considered, for impairment calculation. No definition available.
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- Definition Goodwill and intangible assets. No definition available.
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- Definition Number of internal divisions. No definition available.
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| X | ||||||||||
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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