For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Receivables from contracts with customers, included within Receivables	$ 446		$ 434
Deferred revenue, included within Other liabilities	3,472		$ 3,402
Revenue recognized	285	$ 268
Performance obligations	13,200
2019 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	1,900
2020 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	$ 1,900