Stock Based Compensation - Options Granted to Executives Non Executives and Directors that are Outstanding (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	5,879,573	5,306,506	6,002,174	5,640,619
Weighted Average Exercise Price, Outstanding	$ 41.29	$ 42.69	$ 40.72	$ 41.53
Weighted Average Remaining Contractual Life (in years) - Outstanding	5 years 4 months 24 days
Aggregate Intrinsic Value - Outstanding	$ 23,750
Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	4,475,604
Weighted Average Exercise Price, Outstanding	$ 41.03
Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	1,044,000
Weighted Average Exercise Price, Outstanding	$ 46.84
Non-Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	359,969
Weighted Average Exercise Price, Outstanding	$ 33.03