Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on reclassification from accumulated other comprehensive income	$ 99	$ 155	$ 347	$ 478
OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	(1)	1	(8)	(2)
Tax on reclassification from accumulated other comprehensive income	0	0	0	0
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	52	36	(229)	382
Tax on reclassification from accumulated other comprehensive income	12	2	20	5
Discontinued Operations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	2	(3)	(3)	(5)
Tax on reclassification from accumulated other comprehensive income	21	8	16	14
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	2	0	(1)	3
Tax on reclassification from accumulated other comprehensive income	0	(1)	1	(1)
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	1	0	1	0
Tax on reclassification from accumulated other comprehensive income	(2)	(5)	24	(10)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0	0	0
Tax on reclassification from accumulated other comprehensive income	$ 0	$ 0	$ 0	$ 0