Quarterly report pursuant to Section 13 or 15(d)

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

v3.4.0.3
Share-Based Compensation - Summary of Activity Under Share-Based Compensation Plans (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Awards Outstanding, Beginning Balance 12,076  
Granted, Awards 51  
Exercised, Awards (200)  
Forfeited, Awards (87)  
Awards Outstanding, Ending Balance 11,840 12,076
Awards Exercisable, Ending Balance 7,210  
Weighted Average Exercise Price Outstanding, Beginning Balance $ 38.70  
Granted, Weighted Average Exercise Price 54.75  
Exercised, Weighted Average Exercise Price 27.83  
Forfeited, Weighted Average Exercise Price 47.14  
Weighted Average Exercise Price Outstanding, Ending Balance 38.89 $ 38.70
Exercisable, Weighted Average Exercise Price, Ending Balance $ 34.60  
Weighted Average Remaining Contractual Term Outstanding 6 years 4 months 24 days 6 years 7 months 6 days
Weighted Average Remaining Contractual Term Exercisable 4 years 10 months 24 days  
Aggregate Intrinsic Value Outstanding, Beginning balance $ 216.4  
Aggregate Intrinsic Value Outstanding, Ending balance 286.9 $ 216.4
Exercisable, Aggregate Intrinsic Value, Ending Balance $ 202.5  
Incentive Plan and Independent Directors Stock Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding and nonvested December 31, 2015, Shares 34  
Vested, Shares (1)  
Outstanding and nonvested March 31, 2016, Shares 33 34
Outstanding and nonvested December 31, 2015, Weighted Average Grant Date Fair Value $ 51.08  
Vested, Weighted Average Grant Date Fair Value 59.98  
Outstanding and nonvested March 31, 2016, Weighted Average Grant Date Fair Value $ 50.94 $ 51.08