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Equity And Earnings Per Share (Basic Table) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share:
Net income available for common stockholders	$ 39	$ 31	$ 126	$ 78
Weighted average shares of common stock outstanding:
Weighted Average Number of Shares Outstanding, Basic	74,649,469	71,109,577	72,879,007	69,405,624
Basic earnings per share	$ 0.52	$ 0.44	$ 1.73	$ 1.12
Common Class A
Weighted average shares of common stock outstanding:
Weighted Average Number of Shares Outstanding, Basic	74,649,369	71,109,477	72,878,907	69,405,524
Common Class B
Weighted average shares of common stock outstanding:
Weighted Average Number of Shares Outstanding, Basic	100	100	100	100

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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