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 $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders									$ 348,526	$ 333,360	$ 385,679
Diluted earnings attributable to shareholders									$ 348,526	$ 333,360	$ 385,679
Weighted Average Shares
Weighted average basic shares outstanding									205,994,656	210,422,945	212,117,511
Effect of dilutive potential common shares									900,817	1,512,226	2,916,069
Weighted average diluted shares outstanding									206,895,473	211,935,171	215,033,580
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.41	$ 0.45	$ 0.45	$ 0.39	$ 0.41	$ 0.42	$ 0.40	$ 0.36	$ 1.69	$ 1.58	$ 1.82
Diluted earnings attributable to shareholders per share	$ 0.41	$ 0.45	$ 0.45	$ 0.39	$ 0.40	$ 0.42	$ 0.39	$ 0.36	$ 1.68	$ 1.57	$ 1.79