General - Statement of Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jul. 01, 2019	Jan. 01, 2019	Jul. 01, 2018	Jan. 01, 2018
Increase (decrease) in equity
Balance, beginning of period			$ 21,312
Net income	$ 931	$ 979	3,074	$ 2,702
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(10)	(14)	(1)	(22)
Change in unamortized pension and other postretirement prior service credit	(12)	(15)	(35)	(45)
Balance, end of period	26,140	23,659	26,140	23,659
Retained income
Increase (decrease) in equity
Balance, beginning of period	45,803	43,997	44,033	41,579
Cumulative effect of change in accounting principle					$ 0	$ 21	$ 0	$ 1,088
Net income	931	979	3,074	2,702
Dividends on common stock	(165)	(163)	(498)	(488)
Dividends on preferred stock	(42)	(37)	(103)	(105)
Balance, end of period	46,527	44,776	46,527	44,776
Accumulated other comprehensive income (loss)
Increase (decrease) in equity
Balance, beginning of period	1,760	243	118	1,889
Cumulative effect of change in accounting principle					0	0	0	(910)
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(10)	(14)	(1)	(22)
Change in unamortized pension and other postretirement prior service credit	(12)	(15)	(35)	(45)
Balance, end of period	2,107	144	2,107	144
Previously reported
Increase (decrease) in equity
Net income	1,071	870	3,278	2,521
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(12)	(14)	2	(25)
Change in unamortized pension and other postretirement prior service credit	20	68	155	113
Balance, end of period	26,537	23,633	26,537	23,633
Previously reported | Retained income
Increase (decrease) in equity
Balance, beginning of period	47,542	45,508	45,708	43,162
Cumulative effect of change in accounting principle					0	21	0	1,088
Net income	1,071	870	3,278	2,521
Dividends on common stock	(165)	(163)	(498)	(488)
Dividends on preferred stock	(42)	(37)	(103)	(105)
Balance, end of period	48,406	46,178	48,406	46,178
Previously reported | Accumulated other comprehensive income (loss)
Increase (decrease) in equity
Balance, beginning of period	248	(1,268)	(1,557)	306
Cumulative effect of change in accounting principle					0	0	0	(910)
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(12)	(14)	2	(25)
Change in unamortized pension and other postretirement prior service credit	20	68	155	113
Balance, end of period	625	(1,284)	625	(1,284)
Impact of change | Impact of change
Increase (decrease) in equity
Net income	(140)	109	(204)	181
Unrealized net capital gains and losses	0	0	0	0
Unrealized foreign currency translation adjustments	2	0	(3)	3
Change in unamortized pension and other postretirement prior service credit	(32)	(83)	(190)	(158)
Balance, end of period	(397)	26	(397)	26
Impact of change | Impact of change | Retained income
Increase (decrease) in equity
Balance, beginning of period	(1,739)	(1,511)	(1,675)	(1,583)
Cumulative effect of change in accounting principle					0	0	0	0
Net income	(140)	109	(204)	181
Dividends on common stock	0	0	0	0
Dividends on preferred stock	0	0	0	0
Balance, end of period	(1,879)	(1,402)	(1,879)	(1,402)
Impact of change | Impact of change | Accumulated other comprehensive income (loss)
Increase (decrease) in equity
Balance, beginning of period	1,512	1,511	1,675	1,583
Cumulative effect of change in accounting principle					$ 0	$ 0	$ 0	$ 0
Unrealized net capital gains and losses	0	0	0	0
Unrealized foreign currency translation adjustments	2	0	(3)	3
Change in unamortized pension and other postretirement prior service credit	(32)	(83)	(190)	(158)
Balance, end of period	$ 1,482	$ 1,428	$ 1,482	$ 1,428