Fair Value (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	$ 114	$ 141
Available-for-sale debt securities	103	101
Trading securities	12	12
Total assets	229	254
Fair value of interest rate swap agreement	2	2
Total liabilities	2	2
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	114	141
Total assets	114	141
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	103	101
Trading securities	12	12
Total assets	115	113
Fair value of interest rate swap agreement	2	2
Total liabilities	$ 2	$ 2