U.S. and Europe Retrospective Responsibility Plan Changes in Preferred Stock and Right to Recover Covered Losses (Details) $ / shares in Units, $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2018
USD ($)
$ / shares
shares
|
Sep. 30, 2017
USD ($)
$ / shares
shares
|
Sep. 30, 2016
USD ($)
|
Dec. 31, 2017
USD ($)
|
Sep. 30, 2018
USD ($)
$ / shares
shares
|
Sep. 30, 2017
USD ($)
$ / shares
shares
|
Sep. 30, 2016
USD ($)
|
|||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Beginning Balance | $ 32,760 | $ 32,760 | $ 32,912 | $ 29,842 | |||||||||||||
VE Territory Covered Losses Incurred (Note 14) | (11) | (209) | (34) | ||||||||||||||
Recovery through conversion rate adjustment | 0 | 0 | |||||||||||||||
Ending Balance | $ 34,006 | $ 32,760 | $ 32,912 | 34,006 | 32,760 | 32,912 | |||||||||||
Preferred Stock Available to Recover Covered Losses, Value, As-converted | 11,403 | [1] | 8,048 | [2] | 11,403 | [1] | 8,048 | [2] | |||||||||
Preferred Stock Available to Recover Covered Losses, Value | 5,470 | 5,526 | 5,470 | 5,526 | |||||||||||||
Right to recover for covered losses (Note 2) | (7) | [1] | (52) | [2] | (7) | [1] | (52) | [2] | |||||||||
Preferred Stock Available to Recover Covered Losses, Value, As-converted, Net | 11,396 | [1] | 7,996 | [2] | 11,396 | [1] | 7,996 | [2] | |||||||||
Preferred Stock Available to Recover Covered Losses, Value, Net | $ 5,463 | $ 5,474 | $ 5,463 | $ 5,474 | |||||||||||||
Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Preferred stock, shares outstanding | shares | 5,000,000 | 5,000,000 | 5,000,000 | 5,000,000 | |||||||||||||
Series B Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Recovery through conversion rate adjustment | $ 35 | $ 190 | |||||||||||||||
Preferred Stock Available to Recover Covered Losses, Value, As-converted | $ 4,823 | [1] | $ 3,414 | [2] | 4,823 | [1] | 3,414 | [2] | |||||||||
Preferred stock | $ 2,291 | $ 2,326 | $ 2,291 | $ 2,326 | |||||||||||||
Preferred stock, shares outstanding | shares | 2,000,000 | 2,000,000 | 2,000,000 | 2,000,000 | |||||||||||||
Preferred stock, conversion rate | 12.9550 | 13.077 | [3] | 13.952 | |||||||||||||
Series C Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Recovery through conversion rate adjustment | $ 21 | $ 1 | |||||||||||||||
Preferred Stock Available to Recover Covered Losses, Value, As-converted | $ 6,580 | [1] | $ 4,634 | [2] | 6,580 | [1] | 4,634 | [2] | |||||||||
Preferred stock | $ 3,179 | $ 3,200 | $ 3,179 | $ 3,200 | |||||||||||||
Preferred stock, shares outstanding | shares | 3,000,000 | 3,000,000 | 3,000,000 | 3,000,000 | |||||||||||||
Preferred stock, conversion rate | 13.8880 | 13.948 | |||||||||||||||
Class A common stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Share Price | $ / shares | $ 150.09 | $ 105.24 | $ 150.09 | $ 105.24 | |||||||||||||
Right to Recover for Covered Losses | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Beginning Balance | (52) | $ (52) | $ (34) | 0 | |||||||||||||
VE Territory Covered Losses Incurred (Note 14) | (11) | (11) | (209) | (34) | |||||||||||||
Recovery through conversion rate adjustment | 56 | 191 | |||||||||||||||
Ending Balance | $ (7) | $ (52) | $ (34) | (7) | (52) | (34) | |||||||||||
Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Beginning Balance | 5,526 | 5,526 | 5,717 | 0 | |||||||||||||
Recovery through conversion rate adjustment | (56) | (191) | |||||||||||||||
Ending Balance | 5,470 | 5,526 | $ 5,717 | 5,470 | 5,526 | $ 5,717 | |||||||||||
Preferred Stock | Series B Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Beginning Balance | 2,326 | 2,326 | |||||||||||||||
Recovery through conversion rate adjustment | (35) | ||||||||||||||||
Ending Balance | 2,291 | 2,326 | 2,291 | 2,326 | |||||||||||||
Preferred Stock | Series C Preferred Stock | |||||||||||||||||
Class of Stock [Line Items] | |||||||||||||||||
Beginning Balance | $ 3,200 | 3,200 | |||||||||||||||
Recovery through conversion rate adjustment | (21) | ||||||||||||||||
Ending Balance | $ 3,179 | $ 3,200 | $ 3,179 | $ 3,200 | |||||||||||||
|