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, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 117,760	$ 91,302	$ 224,464	$ 175,126
Diluted earnings attributable to shareholders	$ 117,760	$ 91,302	$ 224,464	$ 175,126
Weighted Average Shares
Weighted average basic shares outstanding	190,679,008	196,451,912	191,150,758	198,772,260
Effect of dilutive potential common shares	1,238,965	674,331	1,274,763	710,672
Weighted average diluted shares outstanding	191,917,973	197,126,243	192,425,521	199,482,932
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.62	$ 0.46	$ 1.17	$ 0.88
Diluted earnings attributable to shareholders per share	$ 0.61	$ 0.46	$ 1.17	$ 0.88