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Stockholders' Equity - Additional Information (Detail) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Oct. 27, 2016
Equity [Line Items] |  |  |  |
Preferred stock shares | 25,000,000 |  |  |
Shares repurchased during the period, shares | 3,980,656 | 0 | 0 |
Shares repurchased during the period, value | $ 161,034,000 |  |  |
Class A Common Stock [Member] |  |  |  |
Equity [Line Items] |  |  |  |
Authorized share repurchase term | 3 years |  |  |
Shares repurchased during the period, value | $ 40,000 |  |  |
Average price per share | $ 40.43 | $ 0 | $ 0 |
Class A Common Stock [Member] | Maximum [Member] |  |  |  |
Equity [Line Items] |  |  |  |
Authorized share repurchase amount |  |  |  | $ 250,000,000

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