Pension and Profit Sharing Plans - Breakdown by Level (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	$ 15,787
Money Market Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	100
Obligations of State and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	659
Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	885
Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	956
Corporate Stocks and Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,187
Level 1 Inputs [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,287
Level 1 Inputs [Member] | Money Market Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	100
Level 1 Inputs [Member] | Corporate Stocks and Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,187
Level 2 Inputs [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	2,500
Level 2 Inputs [Member] | Obligations of State and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	659
Level 2 Inputs [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	885
Level 2 Inputs [Member] | Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	$ 956