Stock-Based Compensation - Summary of Information Regarding Options Outstanding and Exercisable (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Shares	3,855,253
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 3.66
Options Exercisable, Shares	2,881,588
Options Exercisable, Weighted Average Exercise Price	$ 4.27
$0.00 - $2.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 0.00
Exercise Prices, Maximum	$ 2.00
Options Outstanding, Shares	1,072,753
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 1.59
Options Exercisable, Shares	379,706
Options Exercisable, Weighted Average Exercise Price	$ 1.58
$2.01 - $3.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 2.01
Exercise Prices, Maximum	$ 3.00
Options Outstanding, Shares	853,018
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 2.36
Options Exercisable, Shares	598,697
Options Exercisable, Weighted Average Exercise Price	$ 2.37
$3.01 - $4.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 3.01
Exercise Prices, Maximum	$ 4.00
Options Outstanding, Shares	544,806
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 6 months
Options Outstanding, Weighted Average Exercise Price	$ 3.50
Options Exercisable, Shares	522,343
Options Exercisable, Weighted Average Exercise Price	$ 3.49
$4.01 - $5.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 4.01
Exercise Prices, Maximum	$ 5.00
Options Outstanding, Shares	598,444
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 4.66
Options Exercisable, Shares	594,610
Options Exercisable, Weighted Average Exercise Price	$ 4.70
$5.01 - $6.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 5.01
Exercise Prices, Maximum	$ 6.00
Options Outstanding, Shares	164,524
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 5.59
Options Exercisable, Shares	164,524
Options Exercisable, Weighted Average Exercise Price	$ 5.60
$6.01 - $7.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 6.01
Exercise Prices, Maximum	$ 7.00
Options Outstanding, Shares	416,032
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 6 months
Options Outstanding, Weighted Average Exercise Price	$ 6.18
Options Exercisable, Shares	416,032
Options Exercisable, Weighted Average Exercise Price	$ 6.18
$7.01 - $8.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 7.01
Exercise Prices, Maximum	$ 8.00
Options Outstanding, Shares	70,000
Options Outstanding, Weighted Average Remaining Contractual Life	2 years
Options Outstanding, Weighted Average Exercise Price	$ 7.18
Options Exercisable, Shares	70,000
Options Exercisable, Weighted Average Exercise Price	$ 7.18
$8.01 - $9.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 8.01
Exercise Prices, Maximum	$ 9.00
Options Outstanding, Shares	55,000
Options Outstanding, Weighted Average Remaining Contractual Life	1 year 2 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 8.98
Options Exercisable, Shares	55,000
Options Exercisable, Weighted Average Exercise Price	$ 8.98
$9.01 - $10.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 9.01
Exercise Prices, Maximum	$ 10.00
Options Outstanding, Shares	15,000
Options Outstanding, Weighted Average Remaining Contractual Life	1 year 2 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 9.90
Options Exercisable, Shares	15,000
Options Exercisable, Weighted Average Exercise Price	$ 9.90
$10.01 - $16.59 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Prices, Minimum	$ 10.01
Exercise Prices, Maximum	$ 16.59
Options Outstanding, Shares	65,676
Options Outstanding, Weighted Average Remaining Contractual Life	9 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 15.76
Options Exercisable, Shares	65,676
Options Exercisable, Weighted Average Exercise Price	$ 15.76