Activity of the Components of Other Comprehensive Income and Accumulated Other Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pre-tax activity for defined benefit plans, net
Net actuarial gain (loss) arising during the period	$ (38)	$ 7	$ 50
Net activity for accumulated net unrealized gain (loss) on available-for-sale securities
Unrealized holding gains (losses) on available-for-sale securities arising during period	(295)	(63)	201
Reclassification adjustment for net gains included in net income	(4)	(10)	(37)
Net activity for net unrealized gain (loss) on cash flow hedge derivatives
Unrealized holding gains (losses) on cash flow hedge derivatives arising during period	(8)	24	58
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	29	(54)	(45)
Net activity for defined benefit plans, net
Net actuarial gain (loss) arising during the period	(25)	(5)	(33)
Reclassification of amounts to net periodic benefit costs	10	13	12
Total Other Comprehensive Activity
Pre-tax activity total	(451)	(145)	241
Total, Tax	158	50	(85)
Other Comprehensive Income (Loss) Net Of Tax	(293)	(95)	156
Total Accumulated Other Comprehensive Income
Total Accumulated Other Comprehensive Income - Beginning Balance	375	470	314
Other comprehensive income (loss), Net of Tax	(293)	(95)	156
Total Accumulated Other Comprehensive Income - Ending Balance	82	375	470
Accumulated Net Unrealized Investment Gain (Loss)
Pre-tax activity for accumulated net unrealized gain (loss) on available-for-sale securities
Unrealized holding gains on available-for-sale securities arising during period	(454)	(97)	309
Reclassification adjustment for net losses (gains) included in net income	6	(15)	(56)
Net unrealized gains on available-for-sale securities	(448)	(112)	253
Tax effect for accumulated net unrealized gain (loss) on available-for-sale securities
Unrealized holding gains on available-for-sale securities arising during period	159	34	(108)
Reclassification adjustment for net losses (gains) included in net income	(2)	5	19
Net unrealized gains on available-for-sale securities	157	39	(89)
Net activity for accumulated net unrealized gain (loss) on available-for-sale securities
Unrealized holding gains (losses) on available-for-sale securities arising during period	(295)	(63)	201
Reclassification adjustment for net gains included in net income	4	(10)	(37)
Net unrealized gains on available-for-sale securities	(291)	(73)	164
Total Other Comprehensive Activity
Other Comprehensive Income (Loss) Net Of Tax	(291)	(73)	164
Total Accumulated Other Comprehensive Income
Total Accumulated Other Comprehensive Income - Beginning Balance	412	485	321
Other comprehensive income (loss), Net of Tax	(291)	(73)	164
Total Accumulated Other Comprehensive Income - Ending Balance	121	412	485
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Pre-tax activity for net unrealized gain (loss) on cash flow hedge derivatives
Unrealized holding gains on cash flow hedge derivatives arising during period	(13)	37	89
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	(44)	(83)	(69)
Net unrealized gains on cash flow hedge derivatives	(57)	(46)	20
Tax effect for net unrealized gain (loss) on cash flow hedge derivatives
Unrealized holding gains on cash flow hedge derivatives arising during period	5	(13)	(31)
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	15	29	24
Net unrealized gains on cash flow hedge derivatives	20	16	(7)
Net activity for net unrealized gain (loss) on cash flow hedge derivatives
Unrealized holding gains (losses) on cash flow hedge derivatives arising during period	(8)	24	58
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	29	(54)	(45)
Net unrealized gains on cash flow hedge derivatives	(37)	(30)	13
Total Other Comprehensive Activity
Other Comprehensive Income (Loss) Net Of Tax	(37)	(30)	13
Total Accumulated Other Comprehensive Income
Total Accumulated Other Comprehensive Income - Beginning Balance	50	80	67
Other comprehensive income (loss), Net of Tax	(37)	(30)	13
Total Accumulated Other Comprehensive Income - Ending Balance	13	50	80
Accumulated Defined Benefit Plans Adjustment
Pre-tax activity for defined benefit plans, net
Net actuarial gain (loss) arising during the period	38	(7)	(50)
Reclassification of amounts to net periodic benefit costs	(16)	(20)	(18)
Defined benefit plans, net	54	13	(32)
Tax effect for defined benefit plans, net
Net actuarial (gain) loss arising during the period	13	(2)	(17)
Reclassification of amounts to net periodic benefit costs	6	7	6
Defined benefit plans, net	(19)	(5)	11
Net activity for defined benefit plans, net
Net actuarial gain (loss) arising during the period	(25)	5	33
Reclassification of amounts to net periodic benefit costs	(10)	(13)	(12)
Defined benefit plans, net	35	8	(21)
Total Other Comprehensive Activity
Other Comprehensive Income (Loss) Net Of Tax	(35)	(8)	21
Total Accumulated Other Comprehensive Income
Total Accumulated Other Comprehensive Income - Beginning Balance	(87)	(95)	(74)
Other comprehensive income (loss), Net of Tax	(35)	(8)	21
Total Accumulated Other Comprehensive Income - Ending Balance	$ (52)	$ (87)	$ (95)