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Equity And Earnings Per Share (Diluted Table) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Diluted earnings per share:
Net income available for common stockholders	$ 169	$ 76	$ 84
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	73,438,209	69,926,933	66,013,247
Potentially dilutive common shares:
Issuable pursuant to employee incentive plans	828,161	977,988	1,286,166
Weighted Average Number of Shares Outstanding, Diluted	74,266,370	70,904,921	67,299,413
Earnings Per Share, Diluted	$ 2.28	$ 1.07	$ 1.25
Common Class A
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	73,438,109	69,926,833	66,013,147
Common Class B
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	100	100	100

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