2.2.0.7 false Selected Information regarding our Marketable Equity and Debt Securities (Detail) (USD $) 168 - Disclosure - Selected Information regarding our Marketable Equity and Debt Securities (Detail) true false In Millions false false 1 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 shares Standard http://www.xbrl.org/2003/instance shares 0 $ false 2 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 shares Standard http://www.xbrl.org/2003/instance shares 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 $ false 3 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 pure Standard http://www.xbrl.org/2003/instance pure 0 shares Standard http://www.xbrl.org/2003/instance shares 0 $ false 4 USD false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 shares Standard http://www.xbrl.org/2003/instance shares 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 pure Standard http://www.xbrl.org/2003/instance pure 0 $ 5 Trading securities: 3 us-gaap_TradingSecuritiesAbstract us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 6 Net unrealized gain (loss) 4 us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss us-gaap true credit duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 true true false false 8000000 8 false false false 3 true true false false -1000000 -1 false false false 4 true true false false 10000000 10 false false false xbrli:monetaryItemType monetary For trading securities held as of the balance sheet date, this amount represents the difference between the fair value of trading securities and their carrying value (unrealized holding gain or loss). Trading securities are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) and such unrealized holding gain or loss is included in earnings for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 21 -Subparagraph e false 7 Available-for-sale securities: 3 us-gaap_AvailableForSaleSecuritiesAbstract us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 8 Proceeds from sales 4 us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities us-gaap true debit duration No definition available. false false false false false false false false false false false false 1 false true false false 398000000 398 false false false 2 false true false false 531000000 531 false false false 3 false true false false 1538000000 1538 [1] false false false 4 false true false false 1258000000 1258 false false false xbrli:monetaryItemType monetary The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph a Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 18 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph b false 9 Realized gains 4 us-gaap_AvailableForSaleSecuritiesGrossRealizedGains us-gaap true credit duration No definition available. false false false false false false false false false false false false 1 false true false false 16000000 16 [2] false false false 2 false true false false 113000000 113 [2] false false false 3 false true false false 89000000 89 [2] false false false 4 false true false false 174000000 174 [2] false false false xbrli:monetaryItemType monetary This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. 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