Long-Term Debt And Shareholders' Equity (Shareholders' Equity Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	May 22, 2020	Dec. 31, 2019
Shares outstanding (in shares)		164,000,000.0
Common stock, par value (in dollars per share)		$ 0.001		$ 0.001
Common stock and additional paid-in capital		$ 2,700
Common Stock and Additional Paid-in Capital Change		$ 60
Common Stock and Additional Paid-in Capital Percentage Change		2.00%
Common stock repurchased (in shares)	1,700,000
Fair value of stock repurchased	$ 75
Average price per share of stock repurchased (in dollars per share)	$ 45.02
Common stock, terms of conversion		1.10
Accumulated other comprehensive income		$ 355		$ 43
Warrant [Member]
Warrants expired (in shares)			29,200,000
Warrant exercise price (in dollars per share)			$ 33.31