Equity And Earnings Per Share (Diluted Table) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Diluted earnings per share:
Net income available for common stockholders	$ 36	$ 39	$ 117	$ 126
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	76,742,789	74,649,469	75,910,080	72,879,007
Potentially dilutive common shares:
Issuable pursuant to employee incentive plans	606,187	710,620	736,407	866,633
Weighted Average Number of Shares Outstanding, Diluted	77,348,976	75,360,089	76,646,487	73,745,640
Earnings Per Share, Diluted	$ 0.45	$ 0.51	$ 1.52	$ 1.71
Common Class A
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	76,742,689	74,649,369	75,909,980	72,878,907
Common Class B
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	100	100	100	100

Potentially Dilutive Common Shares [Abstract]

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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