Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	$ 3,089	$ 3,308	$ 3,093	$ 3,441
Other comprehensive income (loss) before reclassifications	(59)	5	(128)	(8)
Reclassification adjustments from accumulated other comprehensive income			(3)	(1)
Balance at end of period	3,033	3,537	3,033	3,537
Unrealized Gains (Losses) Available-for-Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	(34)	58	49	91
Other comprehensive income (loss) before reclassifications	(61)	13	(141)	(19)
Reclassification adjustments from accumulated other comprehensive income			(3)	(1)
Balance at end of period	(95)	71	(95)	71
Retirement Plan Liabilities Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	1	1	1	1
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification adjustments from accumulated other comprehensive income			0	0
Balance at end of period	1	1	1	1
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	4	4	3	2
Other comprehensive income (loss) before reclassifications	(3)	1	(2)	3
Reclassification adjustments from accumulated other comprehensive income			0	0
Balance at end of period	1	5	1	5
Other
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	18	17	8	0
Other comprehensive income (loss) before reclassifications	5	(9)	15	8
Reclassification adjustments from accumulated other comprehensive income			0	0
Balance at end of period	23	8	23	8
Total Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance at beginning of period	(11)	80	61	94
Balance at end of period	$ (70)	$ 85	$ (70)	$ 85