Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 270	$ 272	$ 561	$ 532
Changes in:
Net unrealized gains on investments with other-than-temporary impairments	(1)	0	(10)	(4)
Net unrealized gains on other investments	(159)	77	(588)	144
Net unrealized gains on investments	(160)	77	(598)	140
Foreign currency translation adjustment	(52)	42	(40)	53
Pension and postretirement benefits	7	5	17	12
Other comprehensive (loss) income, net of tax	(205)	124	(621)	205
Total comprehensive income (loss)	$ 65	$ 396	$ (60)	$ 737

Unrealized change in value of total investments, after tax.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss, attributable to parent entity.

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