Shares And Stockholders' Equity (Reconciliation Of The Denominator Calculations Of Basic And Diluted EPS) (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reconciliation of the denominator (number of shares) in the calculations of basic and diluted earnings (loss) per common share
Weighted-average shares, as used in basic calculation	204,290,759	218,368,994
Shares to cover exercise of outstanding warrants	173,837	642,787
Shares to cover non-vested stock	1,049,556	1,592,959
Average stock options outstanding during the period	1,519,184	1,969,591
Assumed acquisition of shares with assumed proceeds from exercising outstanding warrants	(29,176)	(81,088)
Assumed acquisition of shares with assumed proceeds and benefits from exercising stock options (at average market price for the period)	(1,041,630)	(1,103,154)
Shares repurchasable from measured but unrecognized stock option expense	(867)	(24,578)
Average deferred compensation shares		922,061
Weighted-average shares, as used in diluted calculation	205,961,663	222,287,572