Shares And Stockholders' Equity (Reconciliation Of The Denominator Calculations Of Basic And Diluted EPS) (Details) - shares		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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		223,555,299	236,463,183	224,581,848	239,069,774
Shares to cover exercise of outstanding warrants		694,403	1,098,405	858,916	1,100,176
Shares to cover non-vested stock	[1]	1,426,550	872,481	1,551,173	967,816
Average stock options outstanding during the period	[1]	2,339,558	2,090,988	2,510,344	1,948,817
Assumed acquisition of shares with assumed proceeds from exercising outstanding warrants		(105,156)	(265,103)	(127,696)	(278,312)
Assumed acquisition of shares with assumed proceeds and benefits from exercising stock options (at average market price for the period)	[1]	(1,464,321)	(1,429,907)	(1,541,738)	(1,364,709)
Shares repurchaseable from measured but unrecognized stock option expense	[1]	(59,959)	(34,492)	(68,519)	(17,797)
Average deferred compensation shares		927,508	1,101,384	938,661	1,070,657
Weighted-average shares, as used in diluted calculation	[1]	227,313,882	239,896,939	228,702,989	242,496,422

[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.