Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares to repurchase	34,000,000
Stock repurchased under the repurchase program	(2,187,382)	(6,714,508)	(2,453,000)
Stock repurchased under the repurchase program, average price	$ 36.34	$ 33.36
Treasury stock, shares held	21,100,000	21,000,000
Treasury stock repurchased	$ 79,500,000	$ 223,993,000	$ 78,718,000
Proceeds from exercise of stock option	42,275,000	30,189,000	13,406,000
Number of stock option exercised	2,100,000	1,500,000
Tax benefit realized for the options exercised	9,200,000	5,400,000
Intrinsic value of options exercised	27,000,000	16,500,000	12,300,000
Weighted average remaining contractual term of all outstanding options (in years)	5.8
Weighted average remaining contractual term of exercisable options (in years)	5.0
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term (in years)	10 years
RSU exercisable period after the grant date	3 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU exercisable period after the grant date	3 years
Period grantees required to remain employed by the company following the date of grant	3 years
Vesting percentage	100.00%
Unamortized compensation costs	10,900,000
Weighted average remaining contractual term of all outstanding options (in years)	1.2
Nonqualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock option exercised	1,864,000
Number of unvested stock options	2,100,000
Unamortized compensation costs	$ 11,900,000
Weighted average remaining contractual term of all outstanding options (in years)	1.7
Equity Incentive Plan 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized grants under the plan	13,000,000
Percentage threshold of outstanding stock for determining availability of grants under Company Plan	7.00%
Number of shares available for grant	12,100,000
Equity Incentive Plan 2010 | Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cap on restricted stock or RSU	2,500,000
Equity Incentive Plan 2010 | Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cap on restricted stock or RSU	200,000