CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 190	$ 313	$ 399	$ 479
Other comprehensive income (loss):
Net unrealized derivative instrument gains (losses) arising during the periods, net of income taxes of ($3), $36, $36 and $70, respectively	(5)	61	60	120
Reclassification adjustment for net derivative (losses) gains included in net income, net of income taxes of ($1), $3, ($2) and $7, respectively	(2)	6	(4)	13
Net unrealized securities available for sale (losses) gains arising during the periods, net of income taxes of ($66), $68, ($12) and $109, respectively	(110)	117	(20)	188
Other-than-temporary impairment not recognized in earnings on securities, net of income taxes of $0, ($1), ($11) and ($12), respectively	1	(2)	(18)	(21)
Reclassification of net securities gains to net income, net of income taxes of ($2), $0, ($5) and ($7), respectively	(5)	2	(9)	(12)
Defined benefit pension plans:
Amortization of actuarial loss, net of income taxes $2, $0, $3 and $1, respectively	2	1	4	2
Total other comprehensive income (loss), net of income taxes	(119)	185	13	290
Total comprehensive income	$ 71	$ 498	$ 412	$ 769