XML 69 R58.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Investments (Net Realized Gains (Losses) From Sales Of Available-For-Sale Securities) (Detail) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Investments [Abstract] |  |
Proceeds from sales | $ 651 | $ 271
Available For Sale Securities Realized Gain Loss [Abstract] |  |
Gross realized gains | 2 | 4
Gross realized losses | $ (6) | $ (1)

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration