Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 942
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-Section S99
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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
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Debt (details) - Payment - USD ($) $ in Millions		6 Months Ended
Debt (details) - Payment - USD ($) $ in Millions	Jun. 02, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Debt Instrument
Debt, principal amount repaid		$ 207	$ 400
Commercial paper, amount outstanding		$ 0		$ 100
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member]
Debt Instrument
Debt, principal amount repaid	$ 107
Interest rate (percent)	6.25%
Percentage of principal amount at which redemption price was set	100.00%