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, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders									$ 457,223	$ 376,888	$ 348,526
Diluted earnings attributable to shareholders									$ 457,223	$ 376,888	$ 348,526
Weighted Average Shares
Weighted average basic shares outstanding									188,941	196,147	205,995
Effect of dilutive potential common shares									1,282	621	900
Weighted average diluted shares outstanding									190,223	196,768	206,895
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.62	$ 0.63	$ 0.62	$ 0.56	$ 0.52	$ 0.53	$ 0.46	$ 0.42	$ 2.42	$ 1.92	$ 1.69
Diluted earnings attributable to shareholders per share	$ 0.61	$ 0.62	$ 0.61	$ 0.55	$ 0.51	$ 0.53	$ 0.46	$ 0.42	$ 2.40	$ 1.92	$ 1.68