XML 116 R97.htm IDEA: XBRL DOCUMENT v3.6.0.2
Defined Benefit Plans - Reconciliation of Level Three Measurements (Detail) - Group annuity/insurance contracts (Level 3) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]    
Beginning balance $ 22.3 $ 21.8
Actual return on assets related to assets still held 0.5 0.5
Ending balance $ 22.8 $ 22.3