Debt (Term Convertible Trust Securities) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	24 Months Ended
	Dec. 31, 2000 integer	Dec. 31, 2013 quarter
Debt Disclosure [Abstract]
Term convertible preferred securities issued by special purpose business trust	10,350,000
Current redemption value of term convertible preferred securities issued by special purpose business trust	$ 50	$ 50
Term convertible preferred securities issued by special purpose business trust par per share	$ 3.375
Term convertible preferred securities issued by special purpose business trust total proceeds	$ 517
Junior subordinated convertible debentures purchased with proceeds from issuance of term convertible preferred securities	$ 517
Term convertible preferred securities dividend rate	6.75%
Term convertible preferred securities common stock conversion ratio		1.4216
Term convertible preferred securities common stock conversion price per share		$ 35.17
Maximum shares parent common stock issuance upon conversion		14.7
Term convertible preferred securities number of quarters dividends may be deferred		20