Outstanding and Exercisable Stock Options by Exercise Price (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	7,584
Weighted-Average Remaining Contractual Life (in years)	1.0
Weighted-Average Exercise Price	$ 53.88
Under $10.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	125
Weighted-Average Remaining Contractual Life (in years)	0.3
Weighted-Average Exercise Price	$ 9.62
$10.01-$20.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	694
Weighted-Average Remaining Contractual Life (in years)	2.8
Weighted-Average Exercise Price	$ 12.59
$20.01-$30.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	60
Weighted-Average Remaining Contractual Life (in years)	0.7
Weighted-Average Exercise Price	$ 23.63
$30.01-$40.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	139
Weighted-Average Remaining Contractual Life (in years)	2.3
Weighted-Average Exercise Price	$ 36.25
Over $40.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	6,566
Weighted-Average Remaining Contractual Life (in years)	0.8
Weighted-Average Exercise Price	$ 59.74