Employee Benefit Plans - Pension Plan Asset Allocations (Detail)	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	65.00%	74.00%
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	2.00%	6.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	33.00%	20.00%