Pension Plan and Life Insurance Contract - Assumptions to Determine Company's Benefit Obligation (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	1.70%	1.60%	1.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	0.00%	0.00%	0.00%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Measurement Date	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016