Shares And Stockholders' Equity (Reconciliation Of The Denominator Calculations Of Basic And Diluted EPS) (Details) - shares		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
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		220,813,693	231,041,085	223,311,993	236,374,010
Shares to cover exercise of outstanding warrants		668,103	1,088,717	795,312	1,096,356
Shares to cover non-vested stock	[1]	1,614,405	1,074,583	1,572,250	1,003,406
Average stock options outstanding during the period	[1]	2,275,826	2,311,106	2,432,171	2,069,579
Assumed acquisition of shares with assumed proceeds from exercising outstanding warrants		(94,338)	(247,909)	(116,577)	(268,177)
Assumed acquisition of shares with assumed proceeds and benefits from exercising stock options (at average market price for the period)	[1]	(1,361,094)	(1,535,425)	(1,481,524)	(1,421,614)
Shares repurchaseable from measured but unrecognized stock option expense	[1]	(44,579)	(70,126)	(60,539)	(35,240)
Average deferred compensation shares				926,612	1,080,205
Weighted-average shares, as used in diluted calculation	[1]	223,872,016	233,662,031	227,379,698	239,898,525

[1] Effective October 1, 2016, we early adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. We have updated certain previously reported interim results and metrics as of January 1, 2016, in accordance with this guidance. For more information, see Note 1 - Earnings Per Share in our 2016 Form 10-K.