v3.20.4
Employee Incentive Plans - Schedule of Restricted Stock Units, Vested and Expected to Vest (Detail)
 12 Months Ended
Dec. 31, 2020
$ / shares
shares
Future Service Required [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Beginning balance of restricted stock units outstanding | shares 4,513,476
Restricted stock units granted | shares 3,527,884
Restricted stock units forfeited | shares (412,352)
Restricted stock units vested | shares (3,637,660)
Ending balance of restricted stock units outstanding | shares 3,991,348
Beginning balance of restricted stock units outstanding, Weighted average grant-date fair value | $ / shares $ 196.69
Restricted stock units granted, Weighted average grant-date fair value | $ / shares 218.17
Restricted stock units forfeited, Weighted average grant-date fair value | $ / shares 208.89
Restricted stock units vested, Weighted average grant-date fair value | $ / shares 204.57
Ending balance of restricted stock units outstanding, Weighted average grant-date fair value | $ / shares $ 207.23
No Future Service Required [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Beginning balance of restricted stock units outstanding | shares 14,698,855
Restricted stock units granted | shares 5,395,829
Restricted stock units forfeited | shares (217,114)
Restricted stock units delivered | shares (8,292,011)
Restricted stock units vested | shares 3,637,660
Ending balance of restricted stock units outstanding | shares 15,223,219
Beginning balance of restricted stock units outstanding, Weighted average grant-date fair value | $ / shares $ 191.25
Restricted stock units granted, Weighted average grant-date fair value | $ / shares 221.94
Restricted stock units forfeited, Weighted average grant-date fair value | $ / shares 198.33
Restricted stock units delivered, Weighted average grant-date fair value | $ / shares 194.55
Restricted stock units vested, Weighted average grant-date fair value | $ / shares 204.57
Ending balance of restricted stock units outstanding, Weighted average grant-date fair value | $ / shares $ 203.41