Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 125	$ 75
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Changes in net unrealized gain on securities	(304)	44
Changes in net gain on cash flow hedging instruments	(18)	(7)
Changes in foreign currency translation adjustments	1	0
OCI, net of tax	(321)	37
Comprehensive income	$ (196)	$ 112

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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