Information about Stock Options and Stock Appreciation Rights Outstanding (Detail) (Stock Option and Stock Appreciation Rights, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares, Outstanding	2,029,582	3,434,256	4,388,862	4,428,339
Weighted Average Remaining Contractual Life	5 years 11 months 5 days
Awards Outstanding, Weighted Average Exercise Price	$ 28.92	$ 26.95	$ 25.94	$ 23.19
6.67 - 11.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 6.67
Range of Exercise Prices, Upper Limit	$ 11.66
Number of Shares, Outstanding	3,000
Weighted Average Remaining Contractual Life	1 year 1 month 6 days
Awards Outstanding, Weighted Average Exercise Price	$ 10.84
Number of Shares, Vested	3,000
Awards Vested, Weighted Average Exercise Price	$ 10.84
11.67 - 16.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 11.67
Range of Exercise Prices, Upper Limit	$ 16.66
Number of Shares, Outstanding	31,686
Weighted Average Remaining Contractual Life	2 years 1 month 6 days
Awards Outstanding, Weighted Average Exercise Price	$ 15.67
Number of Shares, Vested	31,686
Awards Vested, Weighted Average Exercise Price	$ 15.67
16.67 - 21.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 16.67
Range of Exercise Prices, Upper Limit	$ 21.66
Number of Shares, Outstanding	144,285
Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Awards Outstanding, Weighted Average Exercise Price	$ 19.87
Number of Shares, Vested	144,285
Awards Vested, Weighted Average Exercise Price	$ 19.87
21.67 - 26.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 21.67
Range of Exercise Prices, Upper Limit	$ 26.66
Number of Shares, Outstanding	728,053
Weighted Average Remaining Contractual Life	5 years 8 months 12 days
Awards Outstanding, Weighted Average Exercise Price	$ 24.83
Number of Shares, Vested	525,271
Awards Vested, Weighted Average Exercise Price	$ 24.51
26.67 - 31.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 26.67
Range of Exercise Prices, Upper Limit	$ 31.66
Number of Shares, Outstanding	419,148
Weighted Average Remaining Contractual Life	5 years 4 months 24 days
Awards Outstanding, Weighted Average Exercise Price	$ 27.09
Number of Shares, Vested	318,960
Awards Vested, Weighted Average Exercise Price	$ 27.09
31.67 - 36.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 31.67
Range of Exercise Prices, Upper Limit	$ 36.66
Number of Shares, Outstanding	280,146
Weighted Average Remaining Contractual Life	7 years 2 months 12 days
Awards Outstanding, Weighted Average Exercise Price	$ 35.73
Number of Shares, Vested	143,325
Awards Vested, Weighted Average Exercise Price	$ 35.46
36.67 - 38.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit	$ 36.67
Range of Exercise Prices, Upper Limit	$ 38.00
Number of Shares, Outstanding	423,264
Weighted Average Remaining Contractual Life	7 years 2 months 12 days
Awards Outstanding, Weighted Average Exercise Price	$ 37.45
Number of Shares, Vested	183,882
Awards Vested, Weighted Average Exercise Price	$ 37.45