Stock-Based Compensation Plans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Plans		Jun. 30, 2012	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
Expiration term of stock options			5 years
Active equity-based stock plans			2
Stock-based compensation expense			$ 2,030,000	[1]		$ 4,049,000	[1]
Non-cash, Mark-to-market income (loss) related to deferred compensation plan	6,900,000	(9,300,000)	(35,500,000)		(1,500,000)
Shares held in rabbi trust total	2,900,000		2,900,000			2,700,000
Vested shares held in rabbi trust	2,300,000		2,300,000			2,300,000
Equity Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted to employees			388,700		359,700
Granted			$ 71.05		$ 63.37
Stock-based compensation expense			9,500,000		5,200,000
Vesting period of shares granted to employees			Three-year		Three-year
Liability Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted to employees			406,100		355,400
Granted			$ 75.45		$ 63.87
Stock-based compensation expense			$ 11,100,000		$ 10,200,000
Vesting period of shares granted to employees			Three-year		Three-year
Shares Granted To Directors			18,300		14,700
Restricted stock granted average price			$ 77.26		$ 64.35
Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock option outstanding	2,700,000		2,700,000

[1] Includes cost incurred whether capitalized or expensed.