Stockholders' Equity (Details 2) $ / shares in Units, shares in Millions	7 Months Ended	12 Months Ended
	May 31, 2016 USD ($) share_repurchase_program	Oct. 31, 2017 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) $ / shares shares	Oct. 31, 2015 USD ($) $ / shares	Oct. 16, 2017 USD ($)	May 24, 2016 USD ($)	Nov. 30, 2015 USD ($)	Oct. 13, 2015 USD ($)
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		$ (6,599,000,000)
Balance at end of period		$ (2,895,000,000)	$ (6,599,000,000)
Dividends
Cash dividends declared per share (in dollars per share) | $ / shares		$ 0.26	$ 0.22	$ 0.00
Stock Repurchase Program
Stock repurchase program authorized amount								$ 3,000,000,000.00
Number of share repurchase programs | share_repurchase_program	2
Share Repurchase Program
Stock Repurchase Program
Stock repurchase program authorized amount					$ 5,000,000,000.0	$ 3,000,000,000.0
Retired (shares) | shares		136.0	158.0
Open market repurchases (shares) | shares		1.7
Open market repurchases		$ 24,000,000
Remaining authorization		5,800,000,000
Accelerated Share Repurchase Agreement
Stock Repurchase Program
Payment	$ 1,450,000,000						$ 1,075,000,000
Total repurchases of common stock (shares) | shares			148.0
Repurchased		2,600,000,000	$ 2,700,000,000
Net unrealized gains (losses) on available-for-sale securities
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		54,000,000
Other comprehensive (loss) income before reclassifications		(10,000,000)	(2,000,000)	$ (8,000,000)
Reclassifications of (gains) losses into earnings		(3,000,000)
Balance at end of period		29,000,000	54,000,000
Net unrealized gains (losses) on available-for-sale securities | Everett Transaction
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		(9,000,000)
Net unrealized gains (losses) on available-for-sale securities | Seattle SpinCo, Inc.
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		(3,000,000)
Net unrealized gains (losses) on cash flow hedges
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		35,000,000
Other comprehensive (loss) income before reclassifications		52,000,000	212,000,000	$ 412,000,000
Reclassifications of (gains) losses into earnings		(135,000,000)
Balance at end of period		(48,000,000)	35,000,000
Net unrealized gains (losses) on cash flow hedges | Everett Transaction
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		0
Net unrealized gains (losses) on cash flow hedges | Seattle SpinCo, Inc.
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		0
Unrealized components of defined benefit plans
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		(5,642,000,000)
Other comprehensive (loss) income before reclassifications		895,000,000
Reclassifications of (gains) losses into earnings		190,000,000
Balance at end of period		(2,690,000,000)	(5,642,000,000)
Unrealized components of defined benefit plans | Everett Transaction
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		1,820,000,000
Unrealized components of defined benefit plans | Seattle SpinCo, Inc.
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		47,000,000
Cumulative translation adjustment
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		(1,046,000,000)
Other comprehensive (loss) income before reclassifications		(15,000,000)
Reclassifications of (gains) losses into earnings		0
Balance at end of period		(186,000,000)	(1,046,000,000)
Cumulative translation adjustment | Everett Transaction
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		768,000,000
Cumulative translation adjustment | Seattle SpinCo, Inc.
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		107,000,000
Accumulated Other Comprehensive Loss
Components of accumulated other comprehensive income, net of taxes
Balance at beginning of period		(6,599,000,000)
Other comprehensive (loss) income before reclassifications		922,000,000
Reclassifications of (gains) losses into earnings		52,000,000
Balance at end of period		(2,895,000,000)	$ (6,599,000,000)
Accumulated Other Comprehensive Loss | Everett Transaction
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		2,579,000,000
Accumulated Other Comprehensive Loss | Seattle SpinCo, Inc.
Components of accumulated other comprehensive income, net of taxes
Transfer related to spinoff		$ 151,000,000