Employee Benefits and Share-Based Compensation - Summary of Shares Reserved for Future Issuance Under Equity Incentive Plans (Details) shares in Thousands	Mar. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares reserved for future issuance	8,125
2009 Plan | Share options outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares reserved for future issuance	3,544
2009 Plan | Non-vested restricted share awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares reserved for future issuance	738
2009 Plan | Shares authorized for future issuance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares reserved for future issuance	2,140
1997 Employee stock purchase plan | ESPP shares available for future issuance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares reserved for future issuance	1,703