Pension Plan (Details) - Pension plan assets by level within the fair value hierarchy - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	$ 8,984	$ 8,193	$ 7,946
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	8,984	8,193
Fair Value, Inputs, Level 1 [Member] | Equity And Index Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	6,186	5,615
Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	2,798	2,578
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total