Quarterly report pursuant to Section 13 or 15(d)

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

v3.2.0.727
Share-Based Compensation - Summary of Activity Under Share-Based Compensation Plans (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards Outstanding, Beginning Balance 11,169  
Granted, Awards 3,483  
Exercised, Awards (1,836)  
Forfeited, Awards (90)  
Awards Outstanding, Ending Balance 12,726 11,169
Awards Exercisable, Ending Balance 7,342  
Weighted Average Exercise Price Outstanding, Beginning Balance $ 37.46  
Granted, Weighted Average Exercise Price 31.96  
Exercised, Weighted Average Exercise Price 21.77  
Forfeited, Weighted Average Exercise Price 49.79  
Weighted Average Exercise Price Outstanding, Ending Balance 38.13 $ 37.46
Exercisable, Weighted Average Exercise Price, Ending Balance $ 34.02  
Weighted Average Remaining Contractual Term Outstanding 6 years 10 months 24 days 5 years 4 months 24 days
Weighted Average Remaining Contractual Term Exercisable 5 years 1 month 6 days  
Aggregate Intrinsic Value Outstanding, Beginning balance $ 110.6  
Aggregate Intrinsic Value Outstanding, Ending balance 249.0 $ 110.6
Exercisable, Aggregate Intrinsic Value, Ending Balance $ 167.5  
Incentive Plan and Independent Directors Stock Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding and nonvested December 31, 2014, Shares 33  
Granted, Shares 30  
Vested, Shares (23)  
Forfeited, Shares (2)  
Outstanding and nonvested June 30, 2015, Shares 38 33
Outstanding and nonvested December 31, 2014, Weighted Average Grant Date Fair Value $ 63.67  
Granted, Weighted Average Grant Date Fair Value 47.80  
Vested, Weighted Average Grant Date Fair Value 59.98  
Forfeited, Weighted Average Grant Date Fair Value 59.98  
Outstanding and nonvested June 30, 2015, Weighted Average Grant Date Fair Value $ 53.65 $ 63.67