Share-Based Compensation - Additional Information (Detail)	9 Months Ended			0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	May 07, 2014 Stock Option Plan 2014	May 07, 2014 Employee Stock Purchase Plan	May 20, 2014 Directors' Restricted Stock Plan 2014	May 07, 2014 Directors' Restricted Stock Plan 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for grant			2,750,000			250,000
Options granted	2,289,600	2,279,700
Number of additional shares authorized				3,000,000
Issuance of shares under stock purchase plan	671,775	800,461
Restricted shares granted					30,702