Share-Based Compensation - Summary of RSUs and MRSUs (Detail) (Parenthetical) - Multi Year Performance Based Restricted Stock Units [Member] - Minimum [Member] - Ordinary Shares [Member]	Sep. 30, 2017 $ / shares
Vesting Based on $60 Share Price [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average price of shares	$ 60
Vesting Based on $40 Share Price [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average price of shares	40
Vesting Based on $22 Share Price [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average price of shares	$ 22

Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant