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Equity And Earnings Per Share (Basic Table) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per share:
Net income available for common stockholders	$ 41	$ 23	$ 87	$ 47
Weighted average shares of common stock outstanding:
Weighted Average Number of Shares Outstanding, Basic	72,476,729	69,087,853	71,979,104	68,539,526
Basic earnings per share	$ 0.57	$ 0.33	$ 1.21	$ 0.68
Common Class A
Weighted average shares of common stock outstanding:
Weighted Average Number of Shares Outstanding, Basic	72,476,629	69,087,753	71,979,004	68,539,426
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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