Accumulated Other Comprehensive Income (Loss) by Component (Schedule of accumulated other comprehensive income (loss) by component) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period			$ 12,809
Other comprehensive income (loss) before reclassifications	$ (1,429)	$ 336	(3,059)	$ (258)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	(19)	14	(26)	36
Other comprehensive income (loss) after tax (expense) benefit	(1,410)	322	(3,033)	(294)
Total stockholder's equity at end of period	9,512	12,668	9,512	12,668
Reclassification from AOCI, tax	3	(4)	6	(9)
Tax (expense) benefit on other comprehensive income (loss)	355	(78)	778	82
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(1,303)	187	320	803
Total stockholder's equity at end of period	(2,713)	509	(2,713)	509
Net unrealized gains (losses) on investments with an allowance for credit losses | Net unrealized gains (losses) on investments with an allowance for credit losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(6)	0	(2)	0
Other comprehensive income (loss) before reclassifications	(1)	1	(5)	(2)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	1	1	1	(2)
Other comprehensive income (loss) after tax (expense) benefit	(2)	0	(6)	0
Total stockholder's equity at end of period	(8)	0	(8)	0
Reclassification from AOCI, tax	(1)	0	1	(1)
Tax (expense) benefit on other comprehensive income (loss)	0	0	1	0
Net unrealized gains (losses) on investments with an allowance for credit losses | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(572)	1,118	1,039	1,745
Other comprehensive income (loss) before reclassifications	(1,360)	323	(2,972)	(270)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	(14)	23	(15)	57
Other comprehensive income (loss) after tax (expense) benefit	(1,346)	300	(2,957)	(327)
Total stockholder's equity at end of period	(1,918)	1,418	(1,918)	1,418
Reclassification from AOCI, tax	3	(7)	4	(15)
Tax (expense) benefit on other comprehensive income (loss)	356	(75)	780	87
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(598)	(839)	(604)	(848)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	(6)	(10)	(12)	(19)
Other comprehensive income (loss) after tax (expense) benefit	6	10	12	19
Total stockholder's equity at end of period	(592)	(829)	(592)	(829)
Reclassification from AOCI, tax	1	3	3	5
Tax (expense) benefit on other comprehensive income (loss)	(1)	(3)	(3)	(5)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(127)	(92)	(113)	(94)
Other comprehensive income (loss) before reclassifications	(68)	12	(82)	14
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	0	0	0	0
Other comprehensive income (loss) after tax (expense) benefit	(68)	12	(82)	14
Total stockholder's equity at end of period	(195)	(80)	(195)	(80)
Reclassification from AOCI, tax	0	0	0	0
Tax (expense) benefit on other comprehensive income (loss)	$ 0	$ 0	$ 0	$ 0