CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 297	$ 220	$ 763	$ 619
Other comprehensive income (loss):
Net unrealized derivative instrument (losses) gains arising during the periods, net of income taxes of $0, $30, $29 and $66, respectively	(1)	48	45	108
Reclassification adjustment for net derivative gains included in net income, net of income taxes of ($4), ($3), ($14) and ($5), respectively	(6)	(4)	(23)	(8)
Net unrealized securities available for sale (losses) gains arising during the periods, net of income taxes of ($17), $37, $114 and $25, respectively	(28)	61	190	41
Other-than-temporary impairment not recognized in earnings on securities, net of income taxes of $2, ($4), ($11) and ($15), respectively	3	(8)	(18)	(26)
Reclassification of net securities losses (gains) to net income, net of income taxes of $1, $0, ($1) and ($5), respectively	2	0	(1)	(9)
Defined benefit pension plans:
Amortization of actuarial loss, net of income taxes of $2, $0, $5 and $3, respectively	2	3	7	7
Total other comprehensive (loss) income, net of income taxes	(28)	100	200	113
Total comprehensive income	$ 269	$ 320	$ 963	$ 732