Analysis Of Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding-beginning of year	11,620,393	15,185,729	15,509,978
Options Granted	1,072,725	1,338,013	1,358,175
Options Exercised	(5,354,381)	(4,829,892)	(1,273,598)
Options Expired and forfeited	(6,600)	(73,425)	(408,826)
Adjustment to options for stock split - shares	0	(32)	0
Options Outstanding-end of year	7,332,137	11,620,393	15,185,729
Options Exercisable at end of year	4,261,817	8,265,818	11,830,076
Weighted Average Exercise Price Outstanding-beginning of year	$ 35.42	$ 34.09	$ 34.04
Options granted in the period- weighted average exercise price	$ 45.97	$ 44.37	$ 30.86
Options exercised in the period - weighted average exercise price	$ 33.82	$ 33.67	$ 29.73
Options expired and forfeited in the period - weighted average exercise price	$ 44.63	$ 39.17	$ 35.05
Adjustment due to stock split, Weighted Average Exercise Price	$ 0.00	$ 32.96	$ 0.00
Weighted Average Exercise Price Outstanding-end of year	$ 38.14	$ 35.42	$ 34.09
Weighted Average Exercise Price Exercisable at end of year	$ 35.37	$ 36.28	$ 36.10