Shareholders' Equity Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Net unrealized securities gains, before tax [Abstract]
Net unrealized securities gains (losses) arising during the period, before tax	[1]	$ (266)		$ 191		$ (818)		$ 244
Reclassification of net securities (gains) losses included in net income, before tax	[2]	(5)		(21)		(10)		(39)
Impact of DAC, DSIC, unearned revenue, benefit reserves and reinsurance recoverables, before tax		103		(81)		319		(107)
Net unrealized securities gains (losses), before tax		(168)		89		(509)		98
Net unrealized derivatives gains, before tax [Abstract]
Reclassification of net derivative (gains) losses included in net income, before tax		0	[3]	0	[3]	0	[4]	2	[4]
Net unrealized derivatives gains (losses), before tax		0		0		0		2
Defined benefit plans net gain (loss) arising during the period, before tax		0		0		0		7
Defined benefit plans, before tax		0		0		0		7
Foreign currency translation, before tax		(46)		35		(16)		46
Other, before tax		0		0		0		(1)
Total other comprehensive income (loss), before tax		(214)		124		(525)		152
Net unrealized securities gains (losses), tax impact [Abstract]
Net unrealized securities gains (losses) arising during the period, tax	[1]	59		(68)		182		(85)
Reclassification of net securities (gains) losses included in net income, tax		1		8		2		14
Impact of DAC, DSIC, unearned revenue, benefit reserves and reinsurance recoverables, tax		(22)		28		(67)		37
Net unrealized securities gains (losses), tax		(38)		32		(117)		34
Net unrealized derivatives losses, tax impact [Abstract]
Reclassification of net derivative (gains) losses included in net income, tax		0		0		0		(1)
Net unrealized derivatives gains (losses), tax		0		0		0		(1)
Defined benefit plans net gain (loss) arising during the period, tax		0		0		0		(2)
Defined benefit plans, tax		0		0		0		(2)
Foreign currency translation, tax		2		(12)		1		(16)
Other, tax		0		0		0		0
Total other comprehensive income (loss), tax		40		(44)		118		(53)
Net unrealized securities gains (losses), net of tax [Abstract]
Net unrealized securities gains (losses) arising during the period, net of tax	[1]	(207)		123		(636)		159
Reclassification of net securities (gains) losses included in net income, net of tax		(4)		(13)		(8)		(25)
Impact of DAC, DSIC, unearned revenue, benefit reserves and reinsurance recoverables, net of tax		81		(53)		252		(70)
Net unrealized securities gains (losses), net of tax		(130)		57		(392)		64
Net unrealized derivatives losses, net of tax [Abstract]
Reclassification of net derivative (gains) losses included in net income, net of tax		0		0		0		1
Net unrealized derivatives gains (losses), net of tax		0		0		0		1
Defined benefit plans net gain (loss) arising during the period, net of tax		0		0		0		5
Defined benefit plans, net of tax		0		0		0		5
Foreign currency translation adjustment, net of tax		(44)		23		(15)		30
Other, net of tax		0		0		0		(1)
Total other comprehensive income (loss), net of tax		(174)		$ 80		(407)		99
Interest Expense, Borrowings [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		1				1
Net investment income [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		$ 1				$ 1		$ 2

[1] Includes other-than-temporary impairment losses on Available-for-Sale securities related to factors other than credit that were recognized in other comprehensive income (loss) during the period.

[2] Pretax amounts are recorded in net investment income.

[3] Includes a $1 million pretax gain reclassified to interest and debt expense for both the three months ended June 30, 2018 and 2017, and a $1 million pretax loss reclassified to net investment income for both the three months ended June 30, 2018 and 2017.

[4] Includes a $1 million pretax gain reclassified to interest and debt expense for both the six months ended June 30, 2018 and 2017, and a $1 million and $2 million pretax loss reclassified to net investment income for the six months ended June 30, 2018 and 2017, respectively.