Securities Securities - Other than Temporary Impairment, Credit Losses Recognized in Earnings (Detail) - Held-to-maturity Securities [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 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)		$ 0	$ 61,000,000
Increase in credit losses for which an other-than-temporary impairment was previously recognized	$ 0	0
Reduction of credit losses previously recognized on held-to-maturity debt securities due to closure of a VIE			(72,000,000)
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)			0
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	$ 0	$ 11,000,000