Debt (Schedule of Revolving Credit Facility) (Details) - Revolving Credit Facility [Member] - USD ($) $ in Millions			6 Months Ended
		Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Borrowings outstanding	[1]	$ 154	$ 154	$ 272
Senior Unsecured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Proceeds from Lines of Credit			385
Repayments of Lines of Credit			503
Borrowings outstanding	[2]	154	154
Available for borrowing	[3]	$ 1,096	$ 1,096
London Interbank Offered Rate (LIBOR) [Member] | Senior Unsecured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.50%

[1] The weighted average interest rate was 1.5% and 1.6% as of June 30, 2020 and December 31, 2019, respectively.

[2] The Company borrowed $385 million and repaid $503 million under its senior unsecured revolving credit facility during the six months ended June 30, 2020.

[3] The margin for borrowings under the senior unsecured revolving credit facility was 1.5% above LIBOR or EURIBOR at current Company credit ratings.