Preferred and Common Stock - Schedule of Activity for Stock Options (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Stock Option Activity [Line Items]
Number of options, beginning of year	46.8	56.1	65.5
Weighted average exercise price, beginning of year	$ 17.41	$ 19.29	$ 24.44
Number of options, Granted	10.5	4.5	9.0
Weighted average exercise price, granted	$ 10.17	$ 16.24	$ 13.52
Number of options, Exercised	(1.5)	(4.3)	(1.6)
Weighted average exercise price, exercised	$ 8.28	$ 8.59	$ 8.34
Number of options, Expired or forfeited	(10.8)	(9.5)	(16.8)
Weighted average exercise price, expired or forfeited	$ 31.83	$ 31.90	$ 37.21
Number of options, Outstanding end of year	45.0	46.8	56.1
Weighted average exercise price outstanding, end of year	$ 12.58	$ 17.41	$ 19.29
Number of options exercisable, end of year	29.8	28.8	30.2
Weighted average exercise price Exercisable, end of year	$ 13.02	$ 20.90	$ 26.91