XML 30 R20.htm IDEA: XBRL DOCUMENT v3.19.1
Revenue - Additional Information (Detail)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Direct Sales [Member] | Customer Concentration Risk [Member]    
Disaggregation Of Revenue [Line Items]    
Direct sales, percentage of net sales 25.00% 25.00%