Summary of Our Stock Option/Sosar Activity (Detail) (Stock Options, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding at January 1, 2012	6,641,847
Number of Shares, Granted	0
Number of Shares, Exercised	(505,432)
Number of Shares, Forfeited or expired	(745,808)
Number of Shares, Outstanding at December 31, 2012	5,390,607
Number of Shares, Vested and expected to vest	5,365,068
Number of Shares, Exercisable at December 31, 2012	4,853,258
Weighted-average Exercise Price, Outstanding at January 1, 2012	$ 54.69
Weighted-average Exercise Price, Granted	$ 0.00
Weighted-average Exercise Price, Exercised	$ 34.01
Weighted-average Exercise Price, Forfeited or expired	$ 46.69
Weighted-average Exercise Price, Outstanding at December 31, 2011	$ 57.73
Weighted-average Exercise Price, Vested and expected to vest	$ 57.84
Weighted-average Exercise Price, Exercisable at December 31, 2012	$ 59.77
Weighted-average Remaining Contractual Life (Years), Outstanding	4 years 7 months 2 days
Weighted-average Remaining Contractual Life (Years), Vested and expected to vest	4 years 6 months 26 days
Weighted-average Remaining Contractual Life (Years), Exercisable at December 31, 2012	4 years 2 months 19 days
Aggregate Intrinsic Value, Outstanding at December 31, 2012	$ 22,047
Aggregate Intrinsic Value, Vested and expected to vest	21,632
Aggregate Intrinsic Value, Exercisable at December 31, 2012	$ 15,503