Information with Respect to Ordinary Shares that were Surrendered, Repurchased or Redeemed (Detail) - Ordinary Shares A - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed		45,233	3,426,582
Average Price Paid Per Share		$ 40.07	$ 24.57
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program		0	0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs		$ 0	$ 0
January 1-31, 2018
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1],[2]	26,639
Average Price Paid Per Share	[1]	$ 42.02
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]	0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]	$ 0
March 1-31, 2018
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1],[2]	18,594
Average Price Paid Per Share	[1]	$ 37.27
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]	0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]	$ 0
January 1-31, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1],[2]		13,656
Average Price Paid Per Share	[1]		$ 38.21
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]		0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]		$ 0
February 1-28, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1],[2]		15,309
Average Price Paid Per Share	[1]		$ 40.18
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]		0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]		$ 0
May 1 - 31, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1],[2]		586
Average Price Paid Per Share	[1]		$ 38.49
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]		0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]		$ 0
December 1 – 31, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased or Redeemed	[1]		3,397,031
Average Price Paid Per Share	[1]		$ 24.44
Total Number of Shares Purchased as Part of Publicly Announced Plan or Program	[1]		0
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Plans or Programs	[1]		$ 0

[1] Based on settlement date.

[2] Surrendered by employees as payment of taxes withheld on the vesting of restricted stock.