Earnings Per Share - Additional Information (Detail) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common Stock Equivalents
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculations of earnings per share as the effect of including them would have been anti-dilutive	0.3	1.4	4.8
Antidilutive Securities Due to Effect on Period Loss
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculations of earnings per share as the effect of including them would have been anti-dilutive		5.1	2.2
Assumed Conversion Of Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculations of earnings per share as the effect of including them would have been anti-dilutive		66.2	61.8