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Equity And Earnings Per Share (Diluted Table) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Diluted earnings per share:
Net income available for common stockholders	$ 49	$ 46
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	75,101,062	71,475,950
Potentially dilutive common shares:
Issuable pursuant to employee incentive plans	876,449	1,036,512
Weighted Average Number of Shares Outstanding, Diluted	75,977,511	72,512,462
Earnings Per Share, Diluted	$ 0.64	$ 0.63
Common Class A
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	75,100,962	71,475,850
Common Class B
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	100	100

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