Employee Benefit Plans - Pension Plan Asset Allocations (Detail)	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	57.00%	70.00%
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	1.00%	1.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	42.00%	29.00%