CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (UNAUDITED) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 164us-gaap_NetIncomeLoss	$ 104us-gaap_NetIncomeLoss
Net change in unrealized gains (losses), net of tax:
Investment securities	(28)	130
Other-than-temporarily impaired debt securities held-to-maturity	0	1
Derivatives designated as cash flow hedges	(19)	(20)
Pension and post-retirement benefit plans	1	0
Total other comprehensive income (loss)	(46)	111
Comprehensive income	$ 118us-gaap_ComprehensiveIncomeNetOfTax	$ 215us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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-Name Accounting Standards Codification

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss), attributable to parent entity.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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Amount after tax of amount of other than temporary impairment (OTTI) on investment in held-to-maturity debt security, recognized in other comprehensive loss, attributable to parent entity.

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