Securities - Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details) - Held-to-maturity Securities [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance of credit losses on held-to-maturity debt securities for which a portion of an other-than-temporary impairment was recognized in other comprehensive income (loss)		$ 68		$ 61
Increase in credit losses for which an other-than-temporary impairment was previously recognized	$ 0		$ 0
Ending balance of credit losses on held-to-maturity debt securities for which a portion of an other-than-temporary impairment was recognized in other comprehensive income (loss)		72		72
Other Revenues [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Increase in credit losses for which an other-than-temporary impairment was previously recognized	$ 0	$ 4	$ 0	$ 11