CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) shares in Millions, $ in Millions | Total | Cumulative Effect, Period of Adoption, Adjustment | Series B convertible participating preferred stock | Series C convertible participating preferred stock | Class A common stock | Preferred Stock | Preferred StockConversion Of Series A Preferred Stock Upon Sale Into Public Market | Preferred StockSeries A convertible participating preferred stock | [1] | Preferred StockSeries A convertible participating preferred stockConversion Of Series A Preferred Stock Upon Sale Into Public Market | [1] | Preferred StockSeries B convertible participating preferred stock | Preferred StockSeries C convertible participating preferred stock | Common StockClass A common stock | Common StockClass A common stockConversion Of Series A Preferred Stock Upon Sale Into Public Market | Common StockClass A common stockConversion Of Class C Common Stock Upon Sale Into Public Market | [1] | Common StockClass B common stock | Common StockClass C common stock | Common StockClass C common stockConversion Of Class C Common Stock Upon Sale Into Public Market | [1] | Right to Recover for Covered Losses | Additional Paid-In Capital | Additional Paid-In CapitalConversion Of Series A Preferred Stock Upon Sale Into Public Market | Accumulated Income | Accumulated IncomeCumulative Effect, Period of Adoption, Adjustment | Accumulated Other Comprehensive Income (Loss), Net | Accumulated Other Comprehensive Income (Loss), NetCumulative Effect, Period of Adoption, Adjustment |
Increase (Decrease) in Stockholders' Equity [Roll Forward] | | | | | | | | | | | | | | | | | | | | | | | | | | |
Adoption of new accounting standards | | $ 34,684 | | | | | $ 5,462 | | | | | | | | | | | | | $ (171) | $ 16,541 | | $ 13,502 | $ 25 | $ (650) | $ (25) |
Beginning balance (in shares) at Sep. 30, 2019 | | | | | | | | | | | 2 | 3 | 1,718 | | | 245 | 11 | | | | | | | | | |
Beginning balance at Sep. 30, 2019 | | 34,684 | | | | | 5,462 | | | | | | | | | | | | | (171) | 16,541 | | 13,502 | 25 | (650) | (25) |
Increase (Decrease) in Stockholders' Equity [Roll Forward] | | | | | | | | | | | | | | | | | | | | | | | | | | |
Net income | | 3,272 | | | | | | | | | | | | | | | | | | | | | 3,272 | | | |
Other comprehensive income (loss), net of tax | | 335 | | | | | | | | | | | | | | | | | | | | | | | 335 | |
Comprehensive income | | 3,607 | | | | | | | | | | | | | | | | | | | | | | | | |
Adoption of new accounting standards | | 35,270 | | | | | 5,462 | | | | | | | | | | | | | (175) | 16,424 | | 13,899 | 25 | (340) | $ (25) |
VE territory covered losses incurred | | (4) | | | | | | | | | | | | | | | | | | (4) | | | | | | |
Conversion of stock (in shares) | | | | | | | | | | | | | 1 | | | | 0 | [1] | | | | | | | | |
Vesting of restricted stock and performance-based shares (in shares) | | | | | | | | | | | | | 3 | | | | | | | | | | | | | |
Share-based compensation, net of forfeitures | | 116 | | | | | | | | | | | | | | | | | | | 116 | | | | | |
Restricted stock and performance-based shares settled in cash for taxes (in shares) | | | | | | | | | | | | | (1) | | | | | | | | | | | | | |
Restricted stock and performance-based shares settled in cash for taxes | | (147) | | | | | | | | | | | | | | | | | | | (147) | | | | | |
Cash proceeds from issuance of common stock under employee equity plans (in shares) | | | | | | | | | | | | | 1 | | | | | | | | | | | | | |
Cash proceeds from issuance of class A common stock under employee equity plans | | 55 | | | | | | | | | | | | | | | | | | | 55 | | | | | |
Cash dividends declared and paid, at a quarterly amount per Class A share | | (671) | | | | | | | | | | | | | | | | | | | | | (671) | | | |
Repurchase of class A common stock (in shares) | | | | | | (13) | | | | | | | (13) | | | | | | | | | | | | | |
Repurchase of class A common stock | | (2,370) | | | | $ (2,370) | | | | | | | | | | | | | | | (141) | | (2,229) | | | |
Ending balance (in shares) at Dec. 31, 2019 | | | | | | | | | | | 2 | 3 | 1,709 | | | 245 | 11 | | | | | | | | | |
Ending balance at Dec. 31, 2019 | | 35,270 | | | | | 5,462 | | | | | | | | | | | | | (175) | 16,424 | | 13,899 | | (340) | |
Increase (Decrease) in Stockholders' Equity [Roll Forward] | | | | | | | | | | | | | | | | | | | | | | | | | | |
Adoption of new accounting standards | | 35,270 | | | | | 5,462 | | | | | | | | | | | | | (175) | 16,424 | | 13,899 | | (340) | |
Adoption of new accounting standards | | 36,210 | $ 3 | | | | 5,086 | | | | $ 1,106 | $ 1,543 | | | | | | | | (39) | 16,721 | | 14,088 | 3 | 354 | |
Beginning balance (in shares) at Sep. 30, 2020 | | | | | | | | | 0 | | 2 | 3 | 1,683 | | | 245 | 11 | | | | | | | | | |
Beginning balance at Sep. 30, 2020 | | 36,210 | 3 | | | | 5,086 | | | | $ 1,106 | $ 1,543 | | | | | | | | (39) | 16,721 | | 14,088 | 3 | 354 | |
Increase (Decrease) in Stockholders' Equity [Roll Forward] | | | | | | | | | | | | | | | | | | | | | | | | | | |
Net income | | 3,126 | | | | | | | | | | | | | | | | | | | | | 3,126 | | | |
Other comprehensive income (loss), net of tax | | 800 | | | | | | | | | | | | | | | | | | | | | | | 800 | |
Comprehensive income | | 3,926 | | | | | | | | | | | | | | | | | | | | | | | | |
Adoption of new accounting standards | | 36,210 | $ 3 | | | | 3,683 | | | | 1,097 | 1,537 | | | | | | | | (39) | 18,063 | | 14,813 | $ 3 | 1,154 | |
VE territory covered losses incurred | | (10) | | | | | | | | | 0 | 0 | | | | | | | | (10) | | | | | | |
Recovery through conversion rate adjustment | | | | $ 9 | $ 6 | | (15) | | | | $ 9 | $ 6 | | | | | | | | 15 | | | | | | |
Conversion of stock (in shares) | | | | | | | | | | 0 | | | | 20 | 0 | | | | 0 | | | | | | | |
Conversion of stock | | | | | | | | $ (1,388) | | | | | | | | | | | | | | $ 1,388 | | | | |
Vesting of restricted stock and performance-based shares (in shares) | | | | | | | | | | | | | 3 | | | | | | | | | | | | | |
Share-based compensation, net of forfeitures | | 122 | | | | | | | | | | | | | | | | | | | 122 | | | | | |
Restricted stock and performance-based shares settled in cash for taxes (in shares) | | | | | | | | | | | | | (1) | | | | | | | | | | | | | |
Restricted stock and performance-based shares settled in cash for taxes | | (134) | | | | | | | | | | | | | | | | | | | (134) | | | | | |
Cash proceeds from issuance of common stock under employee equity plans (in shares) | [1] | | | | | | | | | | | | 0 | | | | | | | | | | | | | |
Cash proceeds from issuance of class A common stock under employee equity plans | | 61 | | | | | | | | | | | | | | | | | | | 61 | | | | | |
Cash dividends declared and paid, at a quarterly amount per Class A share | | (703) | | | | | | | | | | | | | | | | | | | | | (703) | | | |
Repurchase of class A common stock (in shares) | | | | | | (9) | | | | | | | (9) | | | | | | | | | | | | | |
Repurchase of class A common stock | | (1,796) | | | | $ (1,796) | | | | | | | | | | | | | | | (95) | | (1,701) | | | |
Ending balance (in shares) at Dec. 31, 2020 | | | | | | | | | 0 | | 2 | 3 | 1,696 | | | 245 | 11 | | | | | | | | | |
Ending balance at Dec. 31, 2020 | | 37,679 | | | | | 3,683 | | | | $ 1,097 | $ 1,537 | | | | | | | | (34) | 18,063 | | 14,813 | | 1,154 | |
Increase (Decrease) in Stockholders' Equity [Roll Forward] | | | | | | | | | | | | | | | | | | | | | | | | | | |
Adoption of new accounting standards | | $ 37,679 | | | | | $ 3,683 | | | | $ 1,097 | $ 1,537 | | | | | | | | $ (34) | $ 18,063 | | $ 14,813 | | $ 1,154 | |
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[1] | Increase, decrease or balance is less than one million shares. | |