Incentive Plans - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended			12 Months Ended	1 Months Ended				1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011		Dec. 31, 2007 2012 Annual Incentive Plan	Jun. 20, 2012 2012 Annual Incentive Plan Senior Officers	Jun. 20, 2012 2012 Annual Incentive Plan Senior Officers Minimum	Jun. 20, 2012 2012 Annual Incentive Plan Senior Officers Maximum	Dec. 31, 2007 Employee Stock Purchase Plan	Jan. 31, 2012 Annual Incentive Plan, 2007 Annual Plan	Jan. 31, 2012 Performance-Based Restricted Stock Units	Jan. 31, 2012 Performance-Based Restricted Stock Units Minimum	Jan. 31, 2012 Performance-Based Restricted Stock Units Maximum	Feb. 01, 2012 Time Based Restricted Stock Units (RSU)
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Maximum number of shares available for issuance				8,700,000				980,000
Maximum number of shares available for issuance, annual rate				1.00%
Granted stock options					227,500				1,643,000
Granted stock options, exercise price					$ 45.70				$ 59.655
Stock-based compensation, fair value assumption model					Black-Scholes valuation model				Black-Scholes valuation model	Monte Carlo valuation model
Granted stock options, valuation per option						$ 12.37	$ 13.10		$ 17.74
Granted restricted stock										653,356			40,260
Granted restricted stock, fair value											$ 54.90	$ 63.64	$ 59.33
Granted restricted stock vesting scheme													These shares vest on the third anniversary of the date of grant.
Vested stock options, exercisable period						6 months	3 years
Proceeds from exercise of stock options and employee stock purchase plans	$ 8,752	$ 7,900	[1]
Income tax benefit realized for the tax deductions from option exercises	$ 2,400	$ 7,400

[1] Reclassified to conform to current presentation.