Employee Benefit and Deferred Compensation Plans (Details 5) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair values of defined benefit pension plan assets by category of the firm
Fair value	$ 25,241	$ 36,892
Cash and cash equivalents
Fair values of defined benefit pension plan assets by category of the firm
Fair value	1,639	13,927
U.S. government securities
Fair values of defined benefit pension plan assets by category of the firm
Fair value	2,270	1,883
Corporate debt
Fair values of defined benefit pension plan assets by category of the firm
Fair value	1,991	2,442
Corporate stocks
Fair values of defined benefit pension plan assets by category of the firm
Fair value	17,823	17,383
Investments in registered investment companies
Fair values of defined benefit pension plan assets by category of the firm
Fair value	871	848
Foreign obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	647	308
Municipal obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	101
Quoted Prices In Active Markets for Identical Assets (Level 1)
Fair values of defined benefit pension plan assets by category of the firm
Fair value	20,333	32,158
Quoted Prices In Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Fair values of defined benefit pension plan assets by category of the firm
Fair value	1,639	13,927
Quoted Prices In Active Markets for Identical Assets (Level 1) | U.S. government securities
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate debt
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate stocks
Fair values of defined benefit pension plan assets by category of the firm
Fair value	17,823	17,383
Quoted Prices In Active Markets for Identical Assets (Level 1) | Investments in registered investment companies
Fair values of defined benefit pension plan assets by category of the firm
Fair value	871	848
Quoted Prices In Active Markets for Identical Assets (Level 1) | Foreign obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) | Municipal obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Other Observable Inputs (Level 2)
Fair values of defined benefit pension plan assets by category of the firm
Fair value	4,908	4,734
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Other Observable Inputs (Level 2) | U.S. government securities
Fair values of defined benefit pension plan assets by category of the firm
Fair value	2,270	1,883
Significant Other Observable Inputs (Level 2) | Corporate debt
Fair values of defined benefit pension plan assets by category of the firm
Fair value	1,991	2,442
Significant Other Observable Inputs (Level 2) | Corporate stocks
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Other Observable Inputs (Level 2) | Investments in registered investment companies
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Other Observable Inputs (Level 2) | Foreign obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	647	308
Significant Other Observable Inputs (Level 2) | Municipal obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	101
Significant Unobservable Inputs (Level 3)
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | U.S. government securities
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Corporate debt
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Corporate stocks
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Investments in registered investment companies
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Foreign obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	0	0
Significant Unobservable Inputs (Level 3) | Municipal obligations
Fair values of defined benefit pension plan assets by category of the firm
Fair value	$ 0	$ 0