Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Summary of Activity Under Share-Based Compensation Plans (Detail)

v2.4.0.8
Share-Based Compensation - Summary of Activity Under Share-Based Compensation Plans (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
 3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards Outstanding, Beginning Balance 12,143,000  
Granted, Awards 17,000  
Exercised, Awards (303,000)  
Forfeited, Awards (4,000)  
Awards Outstanding, Ending Balance 11,853,000  
Awards Exercisable, Ending Balance 7,521,000  
Weighted Average Exercise Price Outstanding, Beginning Balance $ 33.24  
Granted, Weighted Average Exercise Price $ 69.80  
Exercised, Weighted Average Exercise Price $ 24.21  
Forfeited, Weighted Average Exercise Price $ 46.01  
Weighted Average Exercise Price Outstanding, Ending Balance $ 33.52  
Exercisable, Weighted Average Exercise Price, Ending Balance $ 20.25  
Weighted Average Remaining Contractual Term Outstanding, Beginning Balance 5 years 3 months 18 days  
Weighted Average Remaining Contractual Term Outstanding, Ending Balance 5 years  
Exercisable, Weighted Average Remaining Contractual Term, Ending Balance 3 years 7 months 6 days  
Aggregate Intrinsic Value Outstanding, Beginning balance $ 552.9  
Aggregate Intrinsic Value Outstanding, Ending balance 307.0  
Exercisable, Aggregate Intrinsic Value, Ending Balance $ 279.5  
Granted, Weighted Average Grant Date Fair Value $ 28.68 $ 11.15
Incentive Plan And Independent Directors Stock Units [Member]
    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding and nonvested December 31, 2013, Shares 144,500  
Granted, Shares     
Vested, Shares (130,700)  
Forfeited, Shares     
Outstanding and nonvested at March 31, 2014, Shares 13,800  
Outstanding and nonvested December 31, 2013, Weighted Average Grant Date Fair Value $ 14.36  
Granted, Weighted Average Grant Date Fair Value     
Vested, Weighted Average Grant Date Fair Value $ 9.62  
Forfeited, Weighted Average Grant Date Fair Value     
Outstanding and nonvested at March 31, 2014, Weighted Average Grant Date Fair Value $ 59.34