Accumulated Other Comprehensive Income (Loss) by Component (Schedule of Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	$ 12,707	$ 12,215
Other comprehensive income (loss) before reclassifications	(444)	714
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	39	(38)
Other comprehensive income (loss) after tax (expense) benefit	(483)	752
Total stockholder's equity at end of period	12,809	12,707
Reclassification from AOCI, tax	(10)	10
Tax (expense) benefit on other comprehensive income (loss)	124	(185)
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	803	51
Total stockholder's equity at end of period	320	803
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	0	0
Other comprehensive income (loss) before reclassifications		(43)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		(43)
Other comprehensive income (loss) after tax (expense) benefit		0
Total stockholder's equity at end of period		0
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]
Reclassification from AOCI, tax		12
Tax (expense) benefit on other comprehensive income (loss)		0
Net unrealized gains (losses) on investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	1,745	1,025
Other comprehensive income (loss) before reclassifications		763
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		43
Other comprehensive income (loss) after tax (expense) benefit		720
Total stockholder's equity at end of period		1,745
Net unrealized gains (losses) on investments | 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	0
Other comprehensive income (loss) before reclassifications	(7)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	(5)
Other comprehensive income (loss) after tax (expense) benefit	(2)
Total stockholder's equity at end of period	(2)	0
Reclassification from AOCI, tax	1
Tax (expense) benefit on other comprehensive income (loss)	1
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	1,745
Other comprehensive income (loss) before reclassifications	(625)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	81
Other comprehensive income (loss) after tax (expense) benefit	(706)
Total stockholder's equity at end of period	1,039	1,745
Reclassification from AOCI, tax	(21)	(12)
Tax (expense) benefit on other comprehensive income (loss)	188	(189)
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(848)	(833)
Other comprehensive income (loss) before reclassifications	207	(53)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	(37)	(38)
Other comprehensive income (loss) after tax (expense) benefit	244	(15)
Total stockholder's equity at end of period	(604)	(848)
Reclassification from AOCI, tax	10	10
Tax (expense) benefit on other comprehensive income (loss)	(65)	4
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(94)	(141)
Other comprehensive income (loss) before reclassifications	(19)	47
Amounts reclassified from accumulated other comprehensive income (loss) net of tax	0	0
Other comprehensive income (loss) after tax (expense) benefit	(19)	47
Total stockholder's equity at end of period	(113)	(94)
Reclassification from AOCI, tax	0	0
Tax (expense) benefit on other comprehensive income (loss)	$ 0	$ 0