XML 61 R67.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Retirement plans - Assumptions Used to Determine Pension Year-End Benefit Obligations (Detail)
Dec. 31, 2019
Dec. 31, 2018
Retirement Plans    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Discount rate (as a percent) 3.29% 4.34%