Net Income (Loss) Per Common Share (Calculation Of Net Income (Loss) Per Common Share) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net Income (Loss) Per Common Share [Abstract]
Net income (loss)	$ (51)	$ 39
Less: Dividends paid on unvested restricted stock awards	(1)	(1)
Total basic and diluted net income (loss)	$ (52)	$ 38
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	1,002,173	1,000,960
Less: Weighted average unvested restricted stock awards (in shares)	(7,457)	(6,934)
Total weighted average shares outstanding - basic (in shares)	994,716	994,026
Basic net income (loss) per common share	$ (0.05)	$ 0.04
Effect of dilutive shares (in shares)		1,502
Total weighted average shares outstanding - diluted (in shares)	994,716	995,528
Diluted net income (loss) per common share	$ (0.05)	$ 0.04