Shareholders' Equity - Summary of Information about Stock Options (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Number of shares
Outstanding Beginning Balance	17,252,879
Options granted	2,822,990
Options exercised	(1,634,494)
Options forfeited	(385,309)
Options cancelled	(222,302)
Outstanding Ending Balance	17,833,764
Exercisable at December 31, 2012	8,449,041
Weighted average exercise price per share
Outstanding Beginning Balance	$ 38.45
Options granted	$ 40.74
Options exercised	$ 17.82
Options forfeited	$ 44.75
Options cancelled	$ 42.95
Outstanding Ending Balance	$ 40.51
Exercisable at December 31, 2012	$ 36.42
Weighted average remaining contractual life
Outstanding at December 31, 2012	5 years 11 months 4 days
Exercisable at December 31, 2012	3 years 7 months 6 days
Aggregate intrinsic value
Outstanding at December 31, 2012	$ 52,718
Exercisable at December 31, 2012	$ 50,178