Earnings Per Common Share (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator (basic and diluted):
Income from continuing operations	$ 140	$ 83	$ 216	$ 145
Less: Allocation to unvested restricted stock awards	3	2	4	3
Income from continuing operations attributable to common shareholders	137	81	212	142
Loss from discontinued operations, net	(1)	(5)	(3)	(14)
Loss from discontinued operations attributable to common shareholders	(1)	(5)	(3)	(14)
Net income available to common shareholders	$ 136	$ 76	$ 209	$ 128
Denominator:
Basic common shares (based upon weighted average) (in shares)	349	349	350	349
Add:
Stock option dilution (in shares)	3	3	3	3
Diluted common shares (in shares)	352	352	353	352