Net Income Per Common Share (Calculations For Basic And Diluted Earnings Per Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income-basic and diluted	$ 122	$ 131	$ 110	$ 154	$ 192	$ 111	$ 32	$ 86	$ 517	$ 421	$ 164
Denominator:
Weighted-average common shares outstanding									163,500,000	162,500,000	162,700,000
Adjusted diluted weighted-average shares									165,400,000	163,700,000	163,300,000
Earnings per share:
Basic	$ 0.75	$ 0.80	$ 0.67	$ 0.95	$ 1.18	$ 0.69	$ 0.20	$ 0.53	$ 3.16	$ 2.59	$ 1.01
Diluted	$ 0.74	$ 0.79	$ 0.66	$ 0.94	$ 1.17	$ 0.68	$ 0.20	$ 0.53	$ 3.12	$ 2.57	$ 1.01
Number of anti-dilutive stock-based awards									400,000	5,900,000	7,800,000
Nonvested shares [Member]
Denominator:
Effect of stock-based awards									1,200,000	500,000	100,000
Stock Options [Member]
Denominator:
Effect of stock-based awards									700,000	700,000	500,000