Stock Option Activity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Year
Number of Shares
Outstanding at beginning of year	9,157,633
Granted	539,322
Exercised	(542,047)
Forfeited/Expired	(1,023,666)
Outstanding at end of year	8,131,242
Options exercisable at year end	5,134,247
Options expected to vest	2,748,974
Weighted Average per Share Exercise Price
Outstanding at beginning of year	$ 19.96
Granted	$ 23.52
Exercised	$ 12.47
Forfeited/Expired	$ 29.93
Outstanding at end of year	$ 19.45
Options exercisable at year end	$ 20.70
Options expected to vest	$ 17.42
Remaining Contractual Life (in years)
Outstanding at end of year	5.23
Options exercisable at year end	3.83
Options expected to vest	7.63
Aggregate Intrinsic Value
Outstanding at end of year	$ 33.8
Options exercisable at year end	17.3
Options expected to vest	$ 15.0