Net Income (Loss) Per Common Share (Calculation Of Net Income (Loss) Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss) Per Common Share [Abstract]
Net income (loss)	$ (28)	$ 38	$ (79)	$ 77
Less: Dividends paid on unvested restricted stock awards		(1)	(1)	(2)
Total basic and diluted net income (loss)	$ (28)	$ 37	$ (80)	$ 75
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	1,044,531	1,002,191	1,026,278	1,001,474
Less: Weighted average unvested restricted stock awards (in shares)	(7,124)	(7,563)	(7,302)	(7,189)
Total weighted average shares outstanding - basic (in shares)	1,037,407	994,628	1,018,976	994,285
Basic net income (loss) per common share	$ (0.03)	$ 0.04	$ (0.08)	$ 0.08
Effect of dilutive shares (in shares)		2,157		2,645
Total weighted average shares outstanding - diluted (in shares)	1,037,407	996,785	1,018,976	996,930
Diluted net income (loss) per common share	$ (0.03)	$ 0.04	$ (0.08)	$ 0.08