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Equity And Earnings Per Share (Diluted Table) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Diluted earnings per share:
Net income available for common stockholders	$ 32	$ 41	$ 81	$ 87
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	75,868,349	72,476,729	75,486,825	71,979,104
Potentially dilutive common shares:
Issuable pursuant to employee incentive plans	726,585	852,767	801,517	944,640
Weighted Average Number of Shares Outstanding, Diluted	76,594,934	73,329,496	76,288,342	72,923,744
Earnings Per Share, Diluted	$ 0.43	$ 0.57	$ 1.07	$ 1.20
Common Class A
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	75,868,249	72,476,629	75,486,725	71,979,004
Common Class B
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	100	100	100	100

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