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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 118,310	$ 102,381	$ 342,774	$ 277,507
Diluted earnings attributable to shareholders	$ 118,310	$ 102,381	$ 342,774	$ 277,507
Weighted Average Shares
Weighted average basic shares outstanding	188,424,400	194,419,071	190,231,986	197,305,251
Effect of dilutive potential common shares	1,217,374	582,196	1,215,810	648,559
Weighted average diluted shares outstanding	189,641,774	195,001,267	191,447,796	197,953,810
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.63	$ 0.53	$ 1.80	$ 1.41
Diluted earnings attributable to shareholders per share	$ 0.62	$ 0.53	$ 1.79	$ 1.40