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Debt - January 2012, May 2014, and November 2015 Exchangeable Senior Notes - Additional Information (Detail) |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jan. 31, 2017 USD ($) | Aug. 31, 2016 USD ($) shares | Mar. 31, 2016 USD ($) | Nov. 30, 2015 USD ($) | May 31, 2014 USD ($) | Jan. 31, 2012 USD ($) | Mar. 31, 2017 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2016 USD ($) shares
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Proceeds from issuance of convertible debt, net of transaction costs |  |  |  |  |  |  | $ 30,000,000 |  |
Convertible senior notes, repayment |  |  |  |  |  |  | 15,107,000 |  |
Convertible senior notes, carrying value, exchanged |  |  |  |  |  |  |  |  | $ 127,300,000
Loss on change in fair value of derivative liabilities |  |  |  |  |  |  |  | $ 1,250,000 |
Interest |  |  |  |  |  |  | $ 4,111,000 | 5,138,000 |
Convertible Debt |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, stated interest rate |  |  |  |  |  |  | 3.50% |  |
Convertible senior notes, principal amount |  |  |  |  |  |  |  |  | 150,000,000
Convertible notes, interest expense |  |  |  |  |  |  | $ 3,400,000 |  |
Interest expense, contractual coupon interest |  |  |  |  |  |  | 1,400,000 |  |
Accrued interest on convertible note |  |  | $ 200,000 |  |  |  | 0 | 200,000 |
Interest |  |  |  |  |  |  | 300,000 | 2,500,000 |
Convertible Debt | Non Cash |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible notes, interest expense |  |  |  |  |  |  | 2,000,000 |  |
Convertible Debt | Cash |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible notes, interest expense |  |  |  |  |  |  | 100,000 |  |
Convertible Debt | Common Shares |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Carrying amount of debt conversion option |  |  |  |  |  |  |  |  | $ 40,100,000
Convertible Debt | American Depositary Shares |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, total ADS into which the debt is exchangeable | shares |  |  |  |  |  |  |  |  | 60,311,188
Transaction costs |  |  |  |  |  |  |  |  | $ 700,000
Convertible Debt | 2012 Notes |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, principal amount |  |  |  | $ 15,100,000 | $ 31,300,000 | $ 150,000,000 | 0 |  | 15,100,000
Convertible senior notes, stated interest rate | 3.50% |  |  |  |  | 3.50% |  |  |
Convertible senior notes, due date | 2032 |  |  |  |  | 2032 |  |  |
Proceeds from issuance of convertible debt, net of transaction costs |  |  |  |  |  | $ 144,300,000 |  |  |
Convertible senior notes, principal amount purchase | $ 15,000,000 |  |  | 16,200,000 |  |  | 15,000,000 |  |
Convertible senior notes, repurchase price at option of the issuer | 100.00% |  |  |  |  | 100.00% |  |  |
Convertible senior notes, aggregate principal amount redeemed |  |  |  |  |  |  | 100,000 |  |
Convertible senior notes, outstanding amount |  |  |  |  |  |  | 0 |  |
Carrying amount of debt conversion option |  |  |  |  |  |  | 23,800,000 |  |
Decrease to additional paid-in capital for repurchase of conversion option in convertible notes |  |  |  |  |  |  | $ 10,100,000 |  |
Note, estimated remaining life |  |  |  |  |  | 24 months | 24 months |  |
Convertible senior notes, discount |  |  |  |  |  |  |  |  | 0
Convertible Debt | 2012 Notes | Other Debt Obligations |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, fair value |  |  |  |  |  |  | $ 126,200,000 |  |
Convertible Debt | 2014 Notes |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, principal amount |  | $ 118,700,000 |  |  | $ 118,700,000 |  | $ 0 |  | 0
Convertible senior notes, stated interest rate |  |  |  |  | 3.50% |  |  |  |
Convertible senior notes, due date |  |  |  |  | 2032 |  |  |  |
Convertible senior notes, principal amount |  |  |  |  | $ 118,700,000 |  |  |  |
Convertible senior notes, repurchase price at option of the issuer |  |  |  |  |  |  | 100.00% |  |
Convertible senior notes, fair value |  |  |  |  |  |  | $ 90,800,000 |  |
Decrease to additional paid-in capital for repurchase of conversion option in convertible notes |  |  |  |  |  |  | 1,300,000 |  |
Convertible senior notes, discount |  |  |  |  |  |  | 27,900,000 |  |
Offering costs |  |  |  |  |  |  | 2,500,000 |  |
Derivative liability at fair value |  |  |  |  |  |  | 3,500,000 |  |
Loss on change in fair value of derivative liabilities |  |  | $ 700,000 |  |  |  |  | 700,000 |
Convertible Debt | 2014 Notes | Final As-Adjusted | American Depositary Shares |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, exchange rate of ADS per $1,000 principal amount of notes |  | 402.0746 |  |  |  |  |  |  |
Convertible senior notes, total ADS into which the debt is exchangeable | shares |  | 47,739,925 |  |  |  |  |  |  |
Convertible Debt | 2015 Notes |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, principal amount |  | $ 31,300,000 |  | $ 31,300,000 |  |  | $ 0 |  | 0
Convertible senior notes, stated interest rate |  |  |  | 3.50% |  |  |  |  |
Convertible senior notes, due date |  |  |  | 2032 |  |  |  |  |
Proceeds from issuance of convertible debt, net of transaction costs |  |  |  | $ 27,500,000 |  |  |  |  |
Convertible senior notes, repayment |  |  |  | $ 15,900,000 |  |  |  |  |
Equity component of convertible notes issuance cost |  |  |  |  |  |  |  |  | 87,400,000
Debt instrument increase accrued interest |  |  |  |  |  |  |  |  | 800,000
Convertible senior notes, repurchase price at option of the issuer |  |  |  |  |  |  | 100.00% |  |
Convertible senior notes, fair value |  |  |  |  |  |  | $ 27,500,000 |  |
Carrying amount of debt conversion option |  |  |  |  |  |  | 11,500,000 |  | $ 11,500,000
Convertible senior notes, discount |  |  |  |  |  |  | 3,800,000 |  |
Offering costs |  |  |  |  |  |  | 100,000 |  |
Derivative liability at fair value |  |  |  |  |  |  | $ 500,000 |  |
Loss on change in fair value of derivative liabilities |  |  |  |  |  |  |  | $ 100,000 |
Convertible Debt | 2015 Notes | Final As-Adjusted | American Depositary Shares |  |  |  |  |  |  |  |  |
Debt Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Convertible senior notes, exchange rate of ADS per $1,000 principal amount of notes |  | 402.0746 |  |  |  |  |  |  |
Convertible senior notes, total ADS into which the debt is exchangeable | shares |  | 12,571,263 |  |  |  |  |  |  |

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