Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Consolidated Statements of Comprehensive Income
Net gain arising during the period, income tax expense				$ 2
Amortization of net (gain) loss included in net income, income tax expense (benefit)	1	1	3	(4)
Prior service credit arising during the period, income tax expense				1
Amortization of prior service credit, income tax benefit				1
Unrealized holding gain (loss) arising during the period, income tax expense (benefit)	(9)	(50)	(5)	12
Reclassification adjustments included in net income, income tax benefit	$ 6	$ 35	$ 12	$ 49

Tax effect on adjustment out of other comprehensive income for prior service costs recognized as a component of net period benefit cost during the period.

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- Definition

Represents the tax effect on amortization adjustment out of other comprehensive income for prior service costs recognized as a component of net period benefit cost during the period.

+ Details

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- Definition

Tax effect on the accumulated change in the value of either the projected benefit obligation or the plans assets resulting from experience different from that assumed or from a change in an actuarial assumption that has not been recognized in net periodic benefit cost pursuant to FAS 87 and 106.

+ References

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- Definition

Tax effect on reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period.

+ References

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- Definition

For each annual statement of income presented, the tax effect of the net gain or loss recognized in other comprehensive income that is a reclassification adjustment of other comprehensive income as a result of being recognized as a component of net periodic benefit cost for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 25

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- Definition

Tax effect on the change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

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