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Capitalization - Secondary Offering (Detail) - Class A common stock - Secondary Offering $ / shares in Units, $ in Millions | 1 Months Ended | 3 Months Ended
--- | --- | ---
Mar. 31, 2017 $ / shares shares | Mar. 31, 2017 USD ($) $ / shares
Class of Stock [Line Items] |  |
Number of shares sold by selling shareholders | 6,331,991 |
Secondary offering price | $ / shares | $ 35.50 | $ 35.50
Additional shares purchase under option granted to underwriters | 949,798 |
Offering costs incurred | $ |  | $ 0.9

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