Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
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, 2017
Mar. 31, 2016
Dec. 31, 2016
SARs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Awards Outstanding, Beginning Balance 11,998    
Granted, Awards 1,345    
Exercised, Awards (481)    
Forfeited, Awards (34)    
Awards Outstanding, Ending Balance 12,828   11,998
Exercisable Awards, Ending Balance 7,223    
Weighted Average Exercise Price Outstanding, Beginning Balance $ 41.52    
Granted, Weighted Average Exercise Price 57.19    
Exercised, Weighted Average Exercise Price 21.39    
Forfeited, Weighted Average Exercise Price 54.97    
Weighted Average Exercise Price Outstanding, Ending Balance 43.88   $ 41.52
Exercisable, Weighted Average Exercise Price, Ending Balance $ 39.34    
Weighted Average Remaining Contractual Term Outstanding 6 years 4 months 24 days   6 years
Exercisable Weighted Average Remaining Contractual Term 4 years 8 months 12 days    
Aggregate Intrinsic Value Outstanding $ 211.4   $ 148.7
Exercisable, Aggregate Intrinsic Value $ 157.1    
Granted, Weighted Average Grant Date Fair Value $ 28.32 $ 21.69  
Incentive Plan and Independent Directors Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding and nonvested December 31, 2016, Shares 26    
Vested, Shares (1)    
Outstanding and nonvested March 31, 2017, Shares 25   26
Outstanding and nonvested December 31, 2016, Weighted Average Grant Date Fair Value $ 62.35    
Vested, Weighted Average Grant Date Fair Value 61.14    
Outstanding and nonvested March 31, 2017, Weighted Average Grant Date Fair Value $ 62.37   $ 62.35