Investments in Operating Joint Ventures (Investments in Operating Joint Ventures) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Investment in operating joint ventures	$ 1,309	$ 1,329	$ 1,483
Dividends received from operating joint ventures	70	93	63
After-tax equity in earnings of operating joint ventures	$ 100	$ 76	$ 49

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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