Incentive Based Compensation Plans - Performance Unit Awards (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Exercise of Option, Tax Benefit	$ 0
Allocated stock-based compensation expense	$ 60,000,000	$ 53,000,000	$ 50,000,000
Expected annual dividend yield	1.20%	1.40%	1.30%
Expected volatility	43.00%	43.00%	42.00%
Risk-free interest rate	2.50%	2.80%	2.10%
Performance Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested units (in shares)	1,282,296
Valuation date stock price (in dollars per share)	$ 16.79	$ 13.69	$ 13.58
Expected annual dividend yield	1.20%	1.50%
Expected volatility	43.00%	41.00%
Risk-free interest rate	2.50%	1.50%
Fair value of stock-based performance units outstanding	$ 20.66	$ 17.29	$ 14.18
Granted Officer [Member] \| Performance Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	656,636	754,140	563,631
Allocated stock-based compensation expense	$ 7,000,000	$ 13,000,000	$ 8,000,000

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

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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