Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Provision for tax benefits related to settlement of employee awards	$ 613
Provisional amount related to remeasurement of deferred tax assets and liabilities, recorded as a component of provision for income taxes	67	$ 301
Reduction in provision for income taxes	$ 67
Effective tax rate	21.00%	35.00%	35.00%
Provisional amount reclassified from deferred tax liabilities for the one-time transition tax		$ 127
Reduction to provision for income taxes for tax credits	$ (28)
Provision for tax benefits related to settlement of employee awards	124	82	$ 162
Provision for income taxes			(51)
Foreign pretax income	86	91	$ 149
State net operating loss carryforwards	71
Federal net operating loss carryforwards	94
Liability for unrecognized tax benefits	435	439
Unrecognized tax benefits, accrued interest	48	44
Unrecognized tax benefits that would impact effective tax rate	137	145
Deferred tax assets, reductions	$ 3	$ 4
State and Local Jurisdiction [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards, expiration date	2021
State and Local Jurisdiction [Member] | Maximum [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards, expiration date	2037