Information with Respect to Ordinary Shares that were Surrendered or Repurchased (Parenthetical) (Detail)	6 Months Ended
Jun. 30, 2012
April 1 to April 30, 2012
Equity, Class of Treasury Stock [Line Items]
Shares surrendered by employees as payment of taxes withheld on vesting of restricted stock	85
June 1 to June 30, 2012
Equity, Class of Treasury Stock [Line Items]
Shares surrendered by employees as payment of taxes withheld on vesting of restricted stock	495

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

No definition available.

Name:	us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration