General - Statement of Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Jan. 01, 2018
Increase (decrease) in equity
Balance, beginning of period	$ 21,312
Net income	1,292	$ 1,006
Unrealized net capital gains and losses	974	(565)
Unrealized foreign currency translation adjustments	5	(2)
Change in unamortized pension and other postretirement prior service credit	(12)	(14)
Balance, end of period	23,418	23,273
Retained income
Increase (decrease) in equity
Balance, beginning of period	44,033	41,579
Cumulative effect of change in accounting principle			$ 21	$ 1,088
Net income	1,292	1,006
Dividends on common stock	(167)	(165)
Dividends on preferred stock	(31)	(29)
Balance, end of period	45,148	43,479
Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	118	1,889
Cumulative effect of change in accounting principle			0	(910)
Unrealized net capital gains and losses	974	(565)
Unrealized foreign currency translation adjustments	5	(2)
Change in unamortized pension and other postretirement prior service credit	(12)	(14)
Balance, end of period	1,085	398
Previously reported
Increase (decrease) in equity
Net income	1,287	975
Unrealized net capital gains and losses	974	(565)
Unrealized foreign currency translation adjustments	7	(4)
Change in unamortized pension and other postretirement prior service credit	10	23
Balance, end of period	23,437	23,277
Previously reported | Retained income
Increase (decrease) in equity
Balance, beginning of period	45,708	43,162
Cumulative effect of change in accounting principle			21	1,088
Net income	1,287	975
Dividends on common stock	(167)	(165)
Dividends on preferred stock	(31)	(29)
Balance, end of period	46,818	45,031
Previously reported | Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	(1,557)	306
Cumulative effect of change in accounting principle			0	(910)
Unrealized net capital gains and losses	974	(565)
Unrealized foreign currency translation adjustments	7	(4)
Change in unamortized pension and other postretirement prior service credit	10	23
Balance, end of period	(566)	(1,150)
Adjustment | Impact of change
Increase (decrease) in equity
Net income	5	31
Unrealized net capital gains and losses	0	0
Unrealized foreign currency translation adjustments	(2)	2
Change in unamortized pension and other postretirement prior service credit	22	(37)
Balance, end of period	(19)	(4)
Adjustment | Impact of change | Retained income
Increase (decrease) in equity
Balance, beginning of period	(1,675)	(1,583)
Cumulative effect of change in accounting principle			0	0
Net income	5	31
Dividends on common stock	0	0
Dividends on preferred stock	0	0
Balance, end of period	(1,670)	(1,552)
Adjustment | Impact of change | Accumulated other comprehensive income
Increase (decrease) in equity
Balance, beginning of period	1,675	1,583
Cumulative effect of change in accounting principle			$ 0	$ 0
Unrealized net capital gains and losses	0	0
Unrealized foreign currency translation adjustments	(2)	2
Change in unamortized pension and other postretirement prior service credit	22	(37)
Balance, end of period	$ 1,651	$ 1,548