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Schedule of Restricted Stock Unit Awards Aggregate Intrinsic Value (Detail) - Restricted Stock Units - USD ($) $ / shares in Thousands, $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award |  |  |
Vested | $ 40,649 | $ 30,008 | $ 32,200
Outstanding | $ 132,875 | $ 95,952 | $ 84,129
Expected to vest | $ 130,594 | $ 91,871 | $ 79,611

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- Definition Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Expected To Vest Intrinsic Value + References No definition available. + Details
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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. + References No definition available. + Details
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- Definition Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options. + References No definition available. + Details
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- Definition Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options. + References No definition available. + Details
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- Details
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