Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Share-Based Compensation - Summary of Activity Under Share-Based Compensation Plans (Detail) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Outstanding and nonvested, Beginning Balance, Number of Shares [1]     3,068,000    
Granted, Number of Shares [2]     1,526,000    
Vested, Number of Shares     (811,000)    
Forfeited, Number of Shares [3]     (111,000)    
Outstanding and nonvested, Ending Balance, Number of Shares [1] 3,672,000   3,672,000   3,068,000
Number of Shares, Expected to vest [4] 3,212,000   3,212,000    
Outstanding and nonvested, Beginning Balance, Weighted Average Grant Date Fair Value Per Share [1]     $ 44.01    
Granted, Weighted Average Grant Date Fair Value Per Share [2]     48.36    
Vested, Weighted Average Grant Date Fair Value Per Share     43.57    
Forfeited, Weighted Average Grant Date Fair Value Per Share [3]     44.95    
Outstanding and nonvested, Ending Balance, Weighted Average Grant Date Fair Value Per Share [1] $ 45.89   45.89   $ 44.01
Expected to vest, Ending Balance, Weighted Average Grant Date Fair Value Per Share [4] $ 45.51   $ 45.51    
SARs [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of Awards Outstanding, Beginning Balance [5],[6]     3,737,000    
Granted, Number of Awards 0 0 0 0  
Exercised, Number of Awards [7]     (1,027,000)    
Forfeited, Number of Awards     (23,000)    
Number of Awards Outstanding, Ending Balance [5] 2,687,000   2,687,000   3,737,000 [6]
Number of Awards Exercisable, Ending Balance [8] 2,687,000   2,687,000    
Number of Awards Vested and expected to vest, Ending Balance 2,687,000   2,687,000    
Weighted Average Exercise Price Per Award Outstanding, Beginning Balance [5],[6]     $ 27.23    
Exercised, Weighted Average Exercise Price Per Award [7]     27.67    
Forfeited, Weighted Average Exercise Price Per Award     25.03    
Weighted Average Exercise Price Per Award Outstanding, Ending Balance [5] $ 27.08   27.08   $ 27.23 [6]
Exercisable, Weighted Average Exercise Price Per Award, Ending Balance [8] 27.08   27.08    
Weighted Average Exercise Price Per Award, Vested and expected to vest, Ending Balance $ 27.08   $ 27.08    
Weighted Average Remaining Contractual Term Outstanding [5]     4 years   4 years 7 months 6 days [6]
Exercisable Weighted Average Remaining Contractual Term [8]     4 years    
Weighted Average Remaining Contractual Term, Vested and expected to vest     4 years    
Aggregate Intrinsic Value Outstanding [5],[9] $ 41.1   $ 41.1   $ 77.8 [6]
Exercisable, Aggregate Intrinsic Value [8],[9] 41.1   41.1    
Aggregate Intrinsic Value, Vested and expected to vest [9] $ 41.1   $ 41.1    
[1] Includes 1,156,954 and 712,596 performance-based stock unit awards as of September 30, 2021 and December 31, 2020, respectively, which represents the maximum amount that can vest.
[2] Includes 447,346 performance-based stock unit awards.
[3] Includes 2,988 performance-based stock unit awards
[4] Includes 768,754 performance-based stock unit awards.
[5] Includes 0.8 million and 1.1 million performance condition SARs as of September 30, 2021 and December 31, 2020, respectively, which represents the maximum amount that can vest
[6] Includes less than 0.1 million market condition SARs as of December 31, 2020.
[7] Includes less than 0.1 million market condition SARs and 0.3 million performance condition SARs.
[8] Includes 0.8 million performance condition SARs.
[9] The intrinsic value is the amount by which the current market value of the underlying stock exceeds the exercise price of the SARs.