Share-Based Compensation - Narrative (Detail) (USD $)	12 Months Ended										3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Maximum	Dec. 31, 2013 Stock Options	Dec. 31, 2012 Stock Options	Dec. 31, 2011 Stock Options	Dec. 31, 2013 Stock Options Minimum	Dec. 31, 2013 Stock Options Maximum	Dec. 31, 2013 Restricted Stock	Dec. 31, 2013 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option term					10 years
Stock options vesting percentage					100.00%
Vested period								6 months	2 years	3 years
Percentage of average closing price to be paid by employees	85.00%
Common stock purchases through advance payroll deductions in a calendar year				$ 25,000
Share-based compensation	1,773,000	1,492,000	1,315,000
Estimated pre-vesting forfeiture rate	5.00%				4.73%	4.77%	5.00%
Unrecognized compensation expense					36,000					2,665,000	0
Unrecognized compensation expense expected recognition period					0 years 4 months 22 days					1 year 4 months 0 days
Weighted-average grant date fair value for stock options (in dollars per share)	$ 5.73	$ 3.97	$ 3.09
Aggregate intrinsic value of stock options exercised	143,000	60,000
Stock Options Exercised	115,000	78,000
Grant date fair value of ESPP options											$ 16,000