Short-Term Borrowings and Long-Term Debt (Schedule of Maturities of Long-term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Due in 2017	$ 20,000	$ 5,000
Due in 2018	25,000	20,000
Due in 2019		10,000
Due in 2020	10,000
Due in 2021		10,000
Thereafter	10,559	10,617
Long-term debt, total	65,559	55,617	$ 74,672
Fixed Rate [Member]
Debt Instrument [Line Items]
Due in 2017	20,000	5,000
Due in 2018	15,000	20,000
Thereafter	10,559	10,617
Long-term debt, total	45,559	35,617
Fixed Rate Convertible [Member]
Debt Instrument [Line Items]
Due in 2018	10,000
Due in 2019		10,000
Long-term debt, total	10,000	10,000
Variable Rate [Member]
Debt Instrument [Line Items]
Due in 2020	10,000
Due in 2021		10,000
Long-term debt, total	$ 10,000	$ 10,000