General - Statement of Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 01, 2019	Jan. 01, 2019	Apr. 01, 2018	Jan. 01, 2018
Increase (decrease) in equity
Balance, beginning of period			$ 21,312
Net income	$ 851	$ 717	2,143	$ 1,723
Unrealized net capital gains and losses	682	(133)	1,656	(698)
Unrealized foreign currency translation adjustments	4	(6)	9	(8)
Change in unamortized pension and other postretirement prior service credit	(11)	(16)	(23)	(30)
Balance, end of period	24,476	23,122	24,476	23,122
Retained income
Increase (decrease) in equity
Balance, beginning of period	45,148	43,479	44,033	41,579
Cumulative effect of change in accounting principle					$ 0	$ 21	$ 0	$ 1,088
Net income	851	717	2,143	1,723
Dividends on common stock	(166)	(160)	(333)	(325)
Dividends on preferred stock	(30)	(39)	(61)	(68)
Balance, end of period	45,803	43,997	45,803	43,997
Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	1,085	398	118	1,889
Cumulative effect of change in accounting principle					0	0	$ 0	(910)
Unrealized net capital gains and losses	682	(133)	1,656	(698)
Unrealized foreign currency translation adjustments	4	(6)	9	(8)
Change in unamortized pension and other postretirement prior service credit	(11)	(16)	(23)	(30)
Balance, end of period	1,760	243	1,760	243
Previously reported
Increase (decrease) in equity
Net income	920	676	2,207	1,651
Unrealized net capital gains and losses	682	(133)	1,656	(698)
Unrealized foreign currency translation adjustments	7	(7)	14	(11)
Change in unamortized pension and other postretirement prior service credit	125	22	135	45
Balance, end of period	24,703	23,122	24,703	23,122
Previously reported | Retained income
Increase (decrease) in equity
Balance, beginning of period	46,818	45,031	45,708	43,162
Cumulative effect of change in accounting principle					0	21		1,088
Net income	920	676	2,207	1,651
Dividends on common stock	(166)	(160)	(333)	(325)
Dividends on preferred stock	(30)	(39)	(61)	(68)
Balance, end of period	47,542	45,508	47,542	45,508
Previously reported | Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	(566)	(1,150)	(1,557)	306
Cumulative effect of change in accounting principle					0	0		(910)
Unrealized net capital gains and losses	682	(133)	1,656	(698)
Unrealized foreign currency translation adjustments	7	(7)	14	(11)
Change in unamortized pension and other postretirement prior service credit	125	22	135	45
Balance, end of period	248	(1,268)	248	(1,268)
Impact of change | Impact of change
Increase (decrease) in equity
Net income	(69)	41	(64)	72
Unrealized net capital gains and losses	0	0	0	0
Unrealized foreign currency translation adjustments	(3)	1	(5)	3
Change in unamortized pension and other postretirement prior service credit	(136)	(38)	(158)	(75)
Balance, end of period	(227)	0	(227)	0
Impact of change | Impact of change | Retained income
Increase (decrease) in equity
Balance, beginning of period	(1,670)	(1,552)	(1,675)	(1,583)
Cumulative effect of change in accounting principle					0	0		0
Net income	(69)	41	(64)	72
Dividends on common stock	0	0	0	0
Dividends on preferred stock	0	0	0	0
Balance, end of period	(1,739)	(1,511)	(1,739)	(1,511)
Impact of change | Impact of change | Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	1,651	1,548	1,675	1,583
Cumulative effect of change in accounting principle					$ 0	$ 0		$ 0
Unrealized net capital gains and losses	0	0	0	0
Unrealized foreign currency translation adjustments	(3)	1	(5)	3
Change in unamortized pension and other postretirement prior service credit	(136)	(38)	(158)	(75)
Balance, end of period	$ 1,512	$ 1,511	$ 1,512	$ 1,511