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Equity And Earnings Per Share (Diluted Table) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Diluted earnings per share:
Net income available for common stockholders	$ 84	$ 49	$ 45
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	66,013,247	61,043,071	56,492,381
Potentially dilutive common shares:
Issuable pursuant to employee incentive plans	1,286,166	1,466,725	1,217,287
Weighted Average Number of Shares Outstanding, Diluted	67,299,413	62,509,796	57,709,668
Earnings Per Share, Diluted	$ 1.25	$ 0.78	$ 0.77
Common Class A
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	66,013,147	61,042,971	56,492,281
Common Class B
Weighted Average Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic	100	100	100

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Potentially Dilutive Common Shares [Abstract]

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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