Basic and Diluted Earnings per Share - Numerator and Denominator of the Basic and Diluted Per Share Computations for Earnings Attributable to Shareholders Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders									$ 590,395	$ 618,199	$ 489,345
Diluted earnings attributable to shareholders									$ 590,395	$ 618,199	$ 489,345
Weighted Average Shares
Weighted average basic shares outstanding									170,899	174,133	179,247
Effect of dilutive potential common shares									3,310	3,700	2,419
Weighted average diluted shares outstanding									174,209	177,833	181,666
Earnings Per Share [Abstract]
Basic earnings attributable to shareholders per share	$ 0.81	$ 0.94	$ 0.90	$ 0.81	$ 1.04	$ 0.94	$ 0.80	$ 0.77	$ 3.45	$ 3.55	$ 2.73
Diluted earnings attributable to shareholders per share	$ 0.79	$ 0.92	$ 0.88	$ 0.80	$ 1.02	$ 0.92	$ 0.79	$ 0.76	$ 3.39	$ 3.48	$ 2.69