Property and Equipment - Property and Equipment Impairment Charges (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Property Plant And Equipment [Line Items] | |||
| Property and equipment impairment charges | $ 4,894 | $ 8,063 | $ 12,210 |
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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 The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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