Share Based Compensation - Schedule of Information with Respect to Outstanding and Exercisable Stock Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Options Outstanding	2,657,723	3,781,964	3,900,435	2,591,887
Options Outstanding, Weighted Average Exercise Price	$ 14.27	$ 12.88	$ 15.15	$ 25.96
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	4 years 11 months 9 days
Options Exercisable, Number Exercisable	1,819,466
Options Exercisable, Weighted Average Exercise Price	$ 18.71
Range of Exercise Prices $2.65 - $2.82 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	2.65
Range of Exercise Prices, Maximum	$ 2.82
Options Outstanding, Number of Options Outstanding	285,416
Options Outstanding, Weighted Average Exercise Price	$ 2.74
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	7 years 1 month 17 days
Options Exercisable, Number Exercisable	176,708
Options Exercisable, Weighted Average Exercise Price	$ 2.76
Range of Exercise Prices $3.93 - $4.15 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	3.93
Range of Exercise Prices, Maximum	$ 4.15
Options Outstanding, Number of Options Outstanding	467,364
Options Outstanding, Weighted Average Exercise Price	$ 4.06
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	9 years 6 months 22 days
Range of Exercise Prices $5.00 - $6.51 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	$ 5.00
Range of Exercise Prices, Maximum	$ 6.51
Options Outstanding, Number of Options Outstanding	269,474
Options Outstanding, Weighted Average Exercise Price	$ 6.04
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	7 years 10 months 13 days
Options Exercisable, Number Exercisable	101,701
Options Exercisable, Weighted Average Exercise Price	$ 6.43
Range of Exercise Prices $7.33 - $7.33 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	7.33
Range of Exercise Prices, Maximum	$ 7.33
Options Outstanding, Number of Options Outstanding	151,230
Options Outstanding, Weighted Average Exercise Price	$ 7.33
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	6 years 4 months 13 days
Options Exercisable, Number Exercisable	62,874
Options Exercisable, Weighted Average Exercise Price	$ 7.33
Range of Exercise Prices $8.63 - $8.63 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	8.63
Range of Exercise Prices, Maximum	$ 8.63
Options Outstanding, Number of Options Outstanding	291,563
Options Outstanding, Weighted Average Exercise Price	$ 8.63
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	1 year 7 months 21 days
Options Exercisable, Number Exercisable	285,507
Options Exercisable, Weighted Average Exercise Price	$ 8.63
Range of Exercise Prices $13.32 - $21.80 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	13.32
Range of Exercise Prices, Maximum	$ 21.80
Options Outstanding, Number of Options Outstanding	335,112
Options Outstanding, Weighted Average Exercise Price	$ 17.66
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	2 years 7 months 2 days
Options Exercisable, Number Exercisable	335,112
Options Exercisable, Weighted Average Exercise Price	$ 17.66
Range of Exercise Prices $22.04 - $22.13 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	22.04
Range of Exercise Prices, Maximum	$ 22.13
Options Outstanding, Number of Options Outstanding	276,000
Options Outstanding, Weighted Average Exercise Price	$ 22.08
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	3 years 6 months 7 days
Options Exercisable, Number Exercisable	276,000
Options Exercisable, Weighted Average Exercise Price	$ 22.08
Range of Exercise Prices $26.15 - $30.67 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	26.15
Range of Exercise Prices, Maximum	$ 30.67
Options Outstanding, Number of Options Outstanding	305,564
Options Outstanding, Weighted Average Exercise Price	$ 29.50
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	3 years 3 months 7 days
Options Exercisable, Number Exercisable	305,564
Options Exercisable, Weighted Average Exercise Price	$ 29.50
Range of Exercise Prices $30.80 - $33.96 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	30.80
Range of Exercise Prices, Maximum	$ 33.96
Options Outstanding, Number of Options Outstanding	258,000
Options Outstanding, Weighted Average Exercise Price	$ 32.30
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	9 months 29 days
Options Exercisable, Number Exercisable	258,000
Options Exercisable, Weighted Average Exercise Price	$ 32.30
Range of Exercise Prices $34.86 - $34.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	34.86
Range of Exercise Prices, Maximum	$ 34.86
Options Outstanding, Number of Options Outstanding	18,000
Options Outstanding, Weighted Average Exercise Price	$ 34.86
Options Outstanding, Weighted Average Remaining Contractual Term (in Years)	1 month 13 days
Options Exercisable, Number Exercisable	18,000
Options Exercisable, Weighted Average Exercise Price	$ 34.86