Derivatives (Schedule Of Interest Rate Swaps) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Jan. 17, 2019	May 22, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted average maturity		2 years 5 months 5 days
Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	$ 200	$ 150	$ 50	$ 150
Weighted average fixed pay rate	2.83%	2.90%
Weighted average 3-month LIBOR receive rate	2.70%	2.38%
Weighted average maturity	2 years 9 months 22 days