Borrowings - Summary of Long-Term Debt, Net of Debt Issuance Costs (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Senior notes	$ 248	$ 248
Trust preferred securities	247	247
Long-term debt	$ 495	$ 495
Interest rate	6.125%	6.125%
3.25%, matures 2032
Debt Instrument [Line Items]
Trust preferred securities	$ 26	$ 26
Interest rate	5.86%	6.07%
3.25%, matures 2033
Debt Instrument [Line Items]
Trust preferred securities	$ 26	$ 26
Interest rate	5.85%	5.69%
3.25%, matures 2033
Debt Instrument [Line Items]
Trust preferred securities	$ 26	$ 26
Interest rate	5.84%	6.05%
2.00%, matures 2035
Debt Instrument [Line Items]
Trust preferred securities	$ 26	$ 26
Interest rate	4.60%	4.44%
2.00%, matures 2035
Debt Instrument [Line Items]
Trust preferred securities	$ 26	$ 26
Interest rate	4.60%	4.44%
1.75%, matures 2035
Debt Instrument [Line Items]
Trust preferred securities	$ 51	$ 51
Interest rate	4.16%	4.54%
1.50%, matures 2035
Debt Instrument [Line Items]
Trust preferred securities	$ 25	$ 25
Interest rate	4.10%	3.94%
1.45%, matures 2037
Debt Instrument [Line Items]
Trust preferred securities	$ 25	$ 25
Interest rate	3.86%	4.24%
2.50%, matures 2037
Debt Instrument [Line Items]
Trust preferred securities	$ 16	$ 16
Interest rate	4.91%	5.29%
Floating Three Month LIBOR \| 3.25%, matures 2032
Debt Instrument [Line Items]
Variable rate on interest rate	3.25%
Floating Three Month LIBOR \| 3.25%, matures 2033
Debt Instrument [Line Items]
Variable rate on interest rate	3.25%
Floating Three Month LIBOR \| 3.25%, matures 2033
Debt Instrument [Line Items]
Variable rate on interest rate	3.25%
Floating Three Month LIBOR \| 2.00%, matures 2035
Debt Instrument [Line Items]
Variable rate on interest rate	2.00%
Floating Three Month LIBOR \| 2.00%, matures 2035
Debt Instrument [Line Items]
Variable rate on interest rate	2.00%
Floating Three Month LIBOR \| 1.75%, matures 2035
Debt Instrument [Line Items]
Variable rate on interest rate	1.75%
Floating Three Month LIBOR \| 1.50%, matures 2035
Debt Instrument [Line Items]
Variable rate on interest rate	1.50%
Floating Three Month LIBOR \| 1.45%, matures 2037
Debt Instrument [Line Items]
Variable rate on interest rate	1.45%
Floating Three Month LIBOR \| 2.50%, matures 2037
Debt Instrument [Line Items]
Variable rate on interest rate	2.50%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

+ References

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

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