Debt (Principal Payments For Investment Agreements, MTNs and VIE Obligations) (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Accrued interest		$ 506	$ 394
Investment Agreement Obligations [Member]
Debt Instrument [Line Items]
2017		56
2018		17
2019		7
2020		35
2021		3
Thereafter		342
Total expected principal payments	[1]	460
Less discount and other adjustments	[2]	61
Total		399
Less unamortized discount		66
Accrued interest		5
Medium Term Notes [Member]
Debt Instrument [Line Items]
2017		36
2018		57
2019		54
2020		0
2021		106
Thereafter		975
Total expected principal payments	[3]	1,228
Less discount and other adjustments	[4]	333
Total		895
Less unamortized discount		279
Accrued interest		3
Fair value adjustments		57
Variable Interest Entity Debt [Member] | International And Structured Finance Insurance [Member]
Debt Instrument [Line Items]
2017		220
2018		238
2019		173
2020		124
2021		140
Thereafter		1,346
Total expected principal payments	[5]	2,241
Net fair value		$ 1,400

[1] Amounts reflect principal due at maturity for investment agreements issued at a discount.

[2] Includes discounts net of carrying amount adjustments of $66 million, net of accrued interest of $5 million.

[3] Amounts reflect principal due at maturity for notes issued at a discount.

[4] Includes discounts net of carrying amount adjustments and bifurcated embedded derivatives of $279 million, fair value adjustments of $57 million, net of accrued interest of $3 million.

[5] Includes $1.4 billion of VIE notes accounted for at fair value as of December 31, 2016.