Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Unrealized gains (losses) on cash flow hedging instruments:
Balance at beginning of period		$ (52)		$ (97)		$ (358)
Net gains arising during period, net of tax		29		38		123
Reclassification adjustment for losses realized in net income, net of tax		8	[1]	7	[1]	138
Total other comprehensive income for period		37		45		261
Balance at end of period		(15)		(52)		(97)
Net gains arising during period, tax		16		20		67
Reclassification adjustment for losses realized in net income, taxes		5		4		76
Unrealized gains (losses) on securities available-for-sale, not other-than temporarily impaired:
Balance at beginning of period		0		0		115
Reclassification adjustment for losses realized in net income, net of tax of $- million, $- million and $(62) million, respectively(2)	[2]	0		0		(115)
Total other comprehensive income (loss) for period		0		0		(115)
Balance at end of period		0		0		0
Reclassification adjustment for losses realized in net income, taxes		0		0		(62)
Unrealized gains (losses) on other-than-temporarily impaired debt securities available-for-sale:
Balance at beginning of period		0		0		1
Reclassification adjustment for gains realized in net income, net of tax of $- million, $- million and $(1) million, respectively(2)	[2]	0		0		(1)
Total other comprehensive income (loss) for period		0		0		(1)
Balance at end of period		0		0		0
Reclassification adjustment for gains realized in net income, tax		0		0		(1)
Pension and postretirement benefit plan liability:
Balance at beginning of period		(13)		(11)		(26)
Change in unfunded pension and postretirement liability, net of tax of $26 million, $(4) million and $7 million, respectively		43		(3)		14
Reclassification adjustment for losses realized in net income, net of tax	[3]	(1)		1		1
Pension and postretirement benefit plan adjustments		42		(2)		15
Balance at end of period		29		(13)		(11)
Change in unfunded pension and postretirement liability, tax		26		(4)		7
Reclassification adjustment for losses realized in net income, tax		(1)		2		1
Foreign currency translation adjustments:
Balance at beginning of period		0		0		11
Translation losses, net of tax of $- million, $- million and $(1) million, respectively		0		0		(5)
Reclassification adjustment for gains realized in net income, net of tax of $- million, $- million and $(9) million, respectively(1)	[1]	0		0		(6)
Total other comprehensive income (loss) for period		0		0		(11)
Balance at end of period		0		0		0
Translation losses, tax		0		0		(1)
Reclassification adjustment for gains realized in net income, taxes		0		0		(9)
Total accumulated other comprehensive loss at end of period		$ 14		$ (65)		$ (108)

[1] See the tables below for the components of the amounts reclassified into income and location in our consolidated statement of income (loss).

[2] The amounts reclassified during 2013 are included in income (loss) from discontinued operations in our consolidated statement of income (loss).

[3] The amounts reclassified during 2015, 2014 and 2013 are included as a component of salaries and employee benefits in our consolidated statement of income (loss).