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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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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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No definition available.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Debt Obligations - Short-term Borrowings and Long-term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Dec. 19, 2013	Dec. 18, 2012	Sep. 17, 2012
Debt Instrument [Line Items]
Short-term borrowings	$ 297	$ 185
Long-term debt	2,914	2,980
Unamortized Debt Issuance Expense	(16)	(18)
Term loan facility
Debt Instrument [Line Items]
Long-term debt	$ 653	$ 675
Weighted-average interest rate on long-term debt	4.50%	4.51%
Revolving credit facility
Debt Instrument [Line Items]
Long-term debt	$ 75	$ 120
Weighted-average interest rate on long-term debt	4.49%	4.49%
5.00% Senior Notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ 600	$ 600
Debt stated interest rate	5.00%	5.00%			5.00%
4.625% Senior Notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500
Debt stated interest rate	4.625%	4.625%		4.625%
5.875% Senior Notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 400	$ 400
Debt stated interest rate	5.875%	5.875%	5.875%
6.375% Senior Notes due 2023
Debt Instrument [Line Items]
Long-term debt	$ 700	$ 700
Debt stated interest rate	6.375%	6.375%	6.375%
Other
Debt Instrument [Line Items]
Long-term debt	$ 2	$ 3
Weighted-average interest rate on long-term debt	0.77%	0.59%
Term loan facility
Debt Instrument [Line Items]
Current portion of Senior Secured Credit Facility	$ 90	$ 84
Weighted-Average interest rate on short-term borrowings	4.50%	4.51%
Trade Receivables Securitization Facility
Debt Instrument [Line Items]
Short-term borrowings	$ 200	$ 100
Weighted-Average interest rate on short-term borrowings	3.36%	3.37%
Other
Debt Instrument [Line Items]
Short-term borrowings	$ 7	$ 1
Weighted-Average interest rate on short-term borrowings	3.71%	4.92%