Benefit Plans - Summary of Characteristics of Options Outstanding (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding as of 12/31/12	2,596
Weighted-Average Remaining Contractual Life (years)	5 years 3 months 18 days
Weighted-Average Exercise Price	$ 25.70
Exercisable as of 12/31/12	2,035
Weighted-Average Exercise price	$ 29.12
0.00 - 6.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Limit	$ 0.00
Exercise Price Range, Upper Limit	$ 6.50
Outstanding as of 12/31/12	569
Weighted-Average Remaining Contractual Life (years)	6 years
Weighted-Average Exercise Price	$ 6.01
Exercisable as of 12/31/12	569
Weighted-Average Exercise price	$ 6.01
6.51 - 12.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Limit	$ 6.51
Exercise Price Range, Upper Limit	$ 12.50
Outstanding as of 12/31/12	276
Weighted-Average Remaining Contractual Life (years)	7 years 3 months 18 days
Weighted-Average Exercise Price	$ 10.42
Exercisable as of 12/31/12	172
Weighted-Average Exercise price	$ 10.37
12.51 - 29.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Limit	$ 12.51
Exercise Price Range, Upper Limit	$ 29.50
Outstanding as of 12/31/12	611
Weighted-Average Remaining Contractual Life (years)	7 years 7 months 6 days
Weighted-Average Exercise Price	$ 15.11
Exercisable as of 12/31/12	154
Weighted-Average Exercise price	$ 18.65
29.51 - 49.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Limit	$ 29.51
Exercise Price Range, Upper Limit	$ 49.50
Outstanding as of 12/31/12	781
Weighted-Average Remaining Contractual Life (years)	3 years 1 month 6 days
Weighted-Average Exercise Price	$ 38.05
Exercisable as of 12/31/12	781
Weighted-Average Exercise price	$ 38.05
49.51 - 69.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Limit	$ 49.51
Exercise Price Range, Upper Limit	$ 69.50
Outstanding as of 12/31/12	359
Weighted-Average Remaining Contractual Life (years)	3 years 8 months 12 days
Weighted-Average Exercise Price	$ 59.87
Exercisable as of 12/31/12	359
Weighted-Average Exercise price	$ 59.87