Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pre- tax
Other comprehensive income (loss)	$ 213	$ (71)	$ 647	$ (288)
Tax
Other comprehensive income (loss)	(45)	15	(136)	61
After- tax
Other comprehensive income (loss), after-tax	168	(56)	511	(227)
Accumulated Net Investment Gain (Loss)
Pre- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	216	(94)	647	(320)
Less: reclassification adjustment of realized capital gains and losses	1	(17)	(6)	(21)
Other comprehensive income (loss)	215	(77)	653	(299)
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(45)	20	(136)	67
Less: reclassification adjustment of realized capital gains and losses	0	4	1	4
Other comprehensive income (loss)	(45)	16	(137)	63
After- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	171	(74)	511	(253)
Less: reclassification adjustment of realized capital gains and losses	1	(13)	(5)	(17)
Other comprehensive income (loss), after-tax	170	(61)	516	(236)
Accumulated Foreign Currency Adjustment
Pre- tax
Other comprehensive income (loss)	(2)	6	(6)	11
Tax
Other comprehensive income (loss)	0	(1)	1	(2)
After- tax
Other comprehensive income (loss), after-tax	$ (2)	$ 5	$ (5)	$ 9

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