Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2014	May 08, 2018	Dec. 31, 2017
Stockholders Equity Note Disclosure [Line Items]
Share repurchase (in shares)			5.5
Stock Repurchased During Period, Value			$ 300,000,000	$ 100,000,000
Cash dividends paid per ordinary share	$ 0.35	$ 0.345	$ 0.70	$ 0.69
Dividends payable	$ 30,700,000		$ 30,700,000				$ 63,100,000
December 2014 Share Repurchase Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Repurchase of shares of our common stock up to a maximum aggregate value					$ 1,000,000,000.0
Share repurchase (in shares)			2.2
Stock Repurchased During Period, Value			$ 150,000,000
Share repurchase program remaining available amount	$ 600,000,070		$ 600,000,070
May 2018 Share Repurchase Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Repurchase of shares of our common stock up to a maximum aggregate value						$ 750,000,000
Common stock authorized for repurchase, expiration date					May 31, 2021
Share repurchase (in shares)			3.3
Stock Repurchased During Period, Value			$ 150,000,000