Franchise fees and gross receipts taxes.

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- Definition

Reduction in annual depreciation expense.

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Summary of significant accounting policies.

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- Definition

The noncurrent portion of the reserve for accumulated deferred investment tax credits as of the balance sheet date. This is the remaining investment credit, which will reduce the cost of services collected from ratepayers by a ratable portion over the investment's regulatory life.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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The component of the allowance for funds used during construction during the period based on an assumed rate of return on equity funds used in financing the construction of regulated assets.

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-Publisher FASB
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Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction.

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Composite depreciation rate for public utility plants in service.

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- Definition

Amount due from customers for fees and charges arising from transactions related to the entity's brokerage activities and operations.

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Amount received for services rendered and products shipped, but not yet billed, for non-contractual agreements due within one year or the normal operating cycle, if longer.

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- Definition

The average discount rate applied to insurance contracts to determine future policy benefits to be paid to or on behalf of policyholders.

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Significant Accounting Policies - Additional Information (Detail) $ in Millions		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 12, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment		2
Percentage of original cost of depreciable property		3.50%	3.70%	3.50%
Depreciation expense		$ 345	$ 332	$ 304
Allowance for funds used during construction rate		6.46%	6.46%	6.46%
Allowance for funds used during construction		$ 15	$ 2	$ 36
Investment tax credits		74			$ 22
Receivables from contracts with customers		226	229
Unbilled revenues		67	66
Franchise fees and gross receipts taxes		$ 120	$ 113	117
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Discount rates used in estimating other self-insurance liabilities		4.00%	2.74%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Discount rates used in estimating other self-insurance liabilities		4.01%	4.00%
PGS [Member]
Summary Of Significant Accounting Policies [Line Items]
Reduction in annual depreciation expense				$ 16
PGS [Member] \| Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Reduction in annual depreciation expense	$ 10