Stock-Based Compensation - Information about Stock Options Outstanding under All Stock Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 5.50
Upper range of exercise prices	$ 11.84
Options Outstanding, Number	1,665,614
Options Outstanding, Weighted Average Contractual Life (Years)	4 years 2 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 8.40
Options Exercisable, Number	941,331
Options Exercisable, Weighted Average Exercise Price	$ 9.35
Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 5.50
Upper range of exercise prices	$ 6.86
Options Outstanding, Number	115,500
Options Outstanding, Weighted Average Contractual Life (Years)	5 years 7 days
Options Outstanding, Weighted Average Exercise Price	$ 6.55
Options Exercisable, Number	81,954
Options Exercisable, Weighted Average Exercise Price	$ 6.64
Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 6.87
Upper range of exercise prices	$ 7.93
Options Outstanding, Number	772,660
Options Outstanding, Weighted Average Contractual Life (Years)	6 years 2 months 23 days
Options Outstanding, Weighted Average Exercise Price	$ 7.26
Options Exercisable, Number	81,923
Options Exercisable, Weighted Average Exercise Price	$ 7.71
Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 8.07
Upper range of exercise prices	$ 8.63
Options Outstanding, Number	104,037
Options Outstanding, Weighted Average Contractual Life (Years)	2 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 8.55
Options Exercisable, Number	104,037
Options Exercisable, Weighted Average Exercise Price	$ 8.55
Range Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 8.76
Upper range of exercise prices	$ 8.76
Options Outstanding, Number	44,000
Options Outstanding, Weighted Average Contractual Life (Years)	2 years 7 months 21 days
Options Outstanding, Weighted Average Exercise Price	$ 8.76
Options Exercisable, Number	44,000
Options Exercisable, Weighted Average Exercise Price	$ 8.76
Range Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 9.09
Upper range of exercise prices	$ 9.09
Options Outstanding, Number	100,000
Options Outstanding, Weighted Average Contractual Life (Years)	2 years 1 month 2 days
Options Outstanding, Weighted Average Exercise Price	$ 9.09
Options Exercisable, Number	100,000
Options Exercisable, Weighted Average Exercise Price	$ 9.09
Range Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 9.11
Upper range of exercise prices	$ 9.12
Options Outstanding, Number	14,627
Options Outstanding, Weighted Average Contractual Life (Years)	2 years 7 months 2 days
Options Outstanding, Weighted Average Exercise Price	$ 9.12
Options Exercisable, Number	14,627
Options Exercisable, Weighted Average Exercise Price	$ 9.12
Range Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 9.16
Upper range of exercise prices	$ 9.16
Options Outstanding, Number	132,000
Options Outstanding, Weighted Average Contractual Life (Years)	3 years 1 month 2 days
Options Outstanding, Weighted Average Exercise Price	$ 9.16
Options Exercisable, Number	132,000
Options Exercisable, Weighted Average Exercise Price	$ 9.16
Range Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 9.19
Upper range of exercise prices	$ 10.25
Options Outstanding, Number	121,780
Options Outstanding, Weighted Average Contractual Life (Years)	2 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 9.70
Options Exercisable, Number	121,780
Options Exercisable, Weighted Average Exercise Price	$ 9.70
Range Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 10.46
Upper range of exercise prices	$ 11.00
Options Outstanding, Number	100,960
Options Outstanding, Weighted Average Contractual Life (Years)	1 year 5 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 10.72
Options Exercisable, Number	100,960
Options Exercisable, Weighted Average Exercise Price	$ 10.72
Range Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range of exercise prices	$ 11.01
Upper range of exercise prices	$ 11.84
Options Outstanding, Number	160,050
Options Outstanding, Weighted Average Contractual Life (Years)	10 months 2 days
Options Outstanding, Weighted Average Exercise Price	$ 11.49
Options Exercisable, Number	160,050
Options Exercisable, Weighted Average Exercise Price	$ 11.49