XML 56 R44.htm IDEA: XBRL DOCUMENT v3.8.0.1
Share-based Compensation - Additional Information (Detail) - shares
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Shares issued under stock purchase plan, stock option exercises and restricted stock 126,511 214,679