Stockholders' Deficit - Narrative (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended	3 Months Ended
	Feb. 28, 2018	Jan. 31, 2018	Jan. 31, 2017
Stockholders' Equity Note [Abstract]
Repurchases of common stock (shares)		20.0	27.0
Subsequent Event [Line Items]
Payment in connection with repurchases of shares		$ 462	$ 386
Share repurchase authorization remaining		$ 2,000
Subsequent event
Subsequent Event [Line Items]
Share repurchases that will be settled in subsequent period (shares)	0.6