Long-Term Debt - Summary of Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total secured and unsecured debt	$ 8,539	$ 7,112
Unamortized discount and debt issuance cost, net	(99)	(104)
Total debt	8,440	7,008
Less: current maturities	(2,145)	(1,009)
Total long-term debt	$ 6,295	5,999
Annual repayment required as percentage of original principal amount	1.00%
Pacific Term Loan B-1
Debt Instrument [Line Items]
Debt instrument, maturity date	Oct. 31, 2018
Debt instrument, interest rate, stated percentage	3.99%
Secured debt	$ 1,048	1,059
Pacific Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, maturity date	Oct. 31, 2018
Line of credit outstanding	$ 0	0
Term Loan Facility
Debt Instrument [Line Items]
Debt instrument, maturity date	Aug. 31, 2022
Debt instrument, interest rate, stated percentage	4.07%
Secured debt	$ 490	495
Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, maturity date	Aug. 31, 2020
Line of credit outstanding	$ 0	0
Certificates
Debt Instrument [Line Items]
Debt instrument, maturity date range, start	Jan. 01, 2018
Debt instrument, maturity date range, end	Dec. 31, 2027
Secured debt	$ 2,380	2,777
Certificates \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.02%
Certificates \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.63%
Notes
Debt Instrument [Line Items]
Debt instrument, maturity date range, start	Jan. 01, 2018
Debt instrument, maturity date range, end	Dec. 31, 2027
Secured debt	$ 1,961	2,488
Notes \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	6.76%
Notes \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.81%
Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, maturity date range, start	Jan. 01, 2020
Debt instrument, maturity date range, end	Dec. 31, 2022
Unsecured debt	$ 2,450	0
Unsecured Notes \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.63%
Unsecured Notes \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.60%
Other Financings
Debt Instrument [Line Items]
Debt instrument, maturity date range, start	Jan. 01, 2019
Debt instrument, maturity date range, end	Dec. 31, 2030
Other debt	$ 210	293
Other Financings \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.75%
Other Financings \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.00%
Other Revolving Credit Facilities
Debt Instrument [Line Items]
Debt instrument, maturity date range, start	Jan. 01, 2018
Debt instrument, maturity date range, end	Dec. 31, 2019
Line of credit outstanding	$ 0	$ 0

Amount of the required periodic payments, as a percentage of principal, applied to principal.

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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Contractual interest rate for funds borrowed, under the debt agreement.

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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.

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No definition available.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Amount, after accumulated amortization, of debt discount (premium).

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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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.

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

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt classified as other.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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