Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Provisional amount related to remeasurement of deferred tax assets and liabilities, recorded as a component of provision for income taxes			$ 67
Effective tax rate	21.00%	21.00%	21.00%	35.00%
Reduction to provision for income taxes for tax credits			$ (28)
Provision for tax benefits related to settlement of employee awards	$ 92	$ 65	124
Foreign pretax income	9	50	$ 86
State net operating loss carryforwards	56
Federal net operating loss carryforwards	127
Liability for unrecognized tax benefits	508	550
Unrecognized tax benefits, accrued interest	73	62
Unrecognized tax benefits that would impact effective tax rate	157	160
Deferred tax assets, reductions	$ 34	$ 34
State and Local Jurisdiction [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards, expiration date	2023
State and Local Jurisdiction [Member] | Maximum [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards, expiration date	2039