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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders									$ 430,807	$ 457,223	$ 376,888
Diluted earnings attributable to shareholders									$ 430,807	$ 457,223	$ 376,888
Weighted Average Shares
Weighted average basic shares outstanding									181,282	188,941	196,147
Effect of dilutive potential common shares									1,422	1,282	621
Weighted average diluted shares outstanding									182,704	190,223	196,768
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.61	$ 0.59	$ 0.64	$ 0.53	$ 0.62	$ 0.63	$ 0.62	$ 0.56	$ 2.38	$ 2.42	$ 1.92
Diluted earnings attributable to shareholders per share	$ 0.61	$ 0.59	$ 0.63	$ 0.53	$ 0.61	$ 0.62	$ 0.61	$ 0.55	$ 2.36	$ 2.40	$ 1.92