Equity Equity (Dividends) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended			114 Months Ended
	Dec. 06, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid			$ 0.1365	$ 0.1365	$ 0.1365	$ 0.1365
Dividends declared on common stock (per share amount)	$ 0.1433	$ 0.28	$ 0.14	$ 0	$ 0.14	$ 0.27	$ 0.13	$ 0	$ 0.13	$ 0.5528	$ 0.5300	$ 0.4900
Treasury Stock, Value, Acquired, Cost Method													$ 1,900
Acquisition of treasury stock (shares)										0			154,300,000
Treasury Stock Acquired, Average Cost Per Share													$ 12.12
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 264								$ 264			$ 264
Treasury stock, shares (in shares)		153,891,260				154,905,595				153,891,260	154,905,595		153,891,260