Impact of COVID-19 (Details) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2020 USD ($) employee	Aug. 01, 2020 USD ($)	Oct. 31, 2020 USD ($) Rate
Unusual or Infrequent Item, or Both [Line Items]
Total financing activities, COVID-19	$ 4,500
Notes subject to exchange and consent offer		$ 465
Headcount reduction, COVID-19 | employee	3,900
Restructuring expense, COVID-19		$ 154
Deferred Occupancy Payments, COVID-19			$ 75
Tax carryback rate, COVID-19 | Rate			35.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | Rate			21.00%
Income tax receivable, COVID-19			$ 705
Employee retention payroll tax credits, COVID-19			60
Deferred Employer Portion of Social Security Taxes, COVID-19			100
Revolving Credit Facility [Member]
Unusual or Infrequent Item, or Both [Line Items]
Proceeds from Lines of Credit			$ 1,500