Other Comprehensive Income and Accumulated Other Comprehensive Income (details) - Reclassifications (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Income tax (expense) benefit	$ 252	$ 109	$ 576	$ 380
Amounts reclassified from accumulated other comprehensive income, net of taxes			(1)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, before tax	(8)
Income tax (expense) benefit	(3)		1
Amounts reclassified from accumulated other comprehensive income, net of taxes	(5)		(1)
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, net of taxes			(33)
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, before tax	(34)		(51)
Income tax (expense) benefit	(12)		(18)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(22)		(33)
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, net of taxes			1
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, before tax	1		2
Income tax (expense) benefit	1		1
Amounts reclassified from accumulated other comprehensive income, net of taxes			1
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, net of taxes			34
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, before tax	25		52
Income tax (expense) benefit	8		18
Amounts reclassified from accumulated other comprehensive income, net of taxes	17		34
Net Unrealized Foreign Currency Translation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, net of taxes			(3)
Net Unrealized Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive income, before tax			(3)
Amounts reclassified from accumulated other comprehensive income, net of taxes			$ (3)