Share-Based Compensation - Additional Information (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]
Unrecognized compensation cost related to unvested share-based equity awards	$ 46,317,000
Weighted average period of recognition of unvested share-based equity awards (in years)	1 year 7 months 2 days
Unrecognized compensation cost related to unvested share-based equity awards, Stock Options	25,311,000
Unrecognized compensation cost related to unvested share-based equity awards, Restricted Stock	21,006,000
Weighted average remaining contractual life of option outstanding	7 years 1 month 17 days
Estimated weighted average fair value of options granted	$ 23.40	$ 18.44	$ 9.30
Total intrinsic value of options exercised	92,864,000
Total intrinsic value of options outstanding and exercisable	76,372,000	67,466,000	40,795,000
Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares of common stock available for issuance	13,500,000
Restricted shares awarded, minimum restriction period	2 years
Restricted shares awarded, maximum restriction period	4 years
Omnibus Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards granted, vesting period	2 years
Stock option awards granted, expiration period	10 years
Omnibus Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards granted, vesting period	4 years
Omnibus Incentive Plan | Deferred Stock Units | Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares granted	12,000	16,000	20,000
Omnibus Incentive Plan | Deferred Stock Units | Non-employee directors | Since 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares granted	118,000
Stock Option Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares of common stock available for issuance	16,400,000
Common stock shares granted	570,700	1,276,500	1,615,812
Stock option awards granted, vesting period	3 years
Stock Option Plans | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards granted, expiration period	10 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair values at the grant dates of grants awarded	$ 70.12	$ 42.54	$ 28.95
Total intrinsic value of restricted stock expected to vest	45,814,000
Non Employee Directors, Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares granted	8,000
Options granted, exercise period	No later than 10 years from the date of grant.
Non Employee Directors, Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares of common stock available for issuance	400,000
Options granted, maximum exercise period	10 years
Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares of common stock authorized	500,000
Shares of common stock earned	234,000
Additional shares issued to retired directors	230,000
Liabilities under share plan	19,699,000	13,933,000
Long Term Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liabilities under share plan	$ 66,586,000	$ 93,765,000