XML 72 R60.htm IDEA: XBRL DOCUMENT v3.10.0.1
Income Per Share Information - Additional Information (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Contingently Issuable Shares [Member]        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Shares excluded in computation of diluted income per share 34,470 384,775 28,922 1,141,522