Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of employer contribution to match participant contribution in defined contribution plan, net	100.00%
Cost of defined benefit plans	$ 532	$ 499	$ 471
Defined benefit plan cost	11	9	14
Defined benefit plan obligation	$ 63	68
Defined Contribution Benefit Plans [Member] | Minimum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of employer contribution to match participant contribution in defined contribution plan	3.00%
Defined Contribution Benefit Plans [Member] | Maximum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentage of employer contribution to match participant contribution in defined contribution plan	9.00%
Restoration Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Number of hours of service required to qualify for the plan	1,000 or more hours
Noncontributory and nonqualified plan, benefit expense	$ 44	22	40
Noncontributory and nonqualified plan, accrued benefits liabilities	227	205
Supplemental Executive Retirement Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan cost	19	26	$ 28
Defined benefit plan obligation	$ 192	$ 195