Long-Term Borrowings (Minimum Annual Retirements of Long-Term Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Aggregate minimum annual retirements of long-term borrowings in future periods:
2015	$ 2,945
2016	2,330
2017	82,390
2018	1,426
2019	3,901
Thereafter	20,678
Long-term borrowings	$ 113,670	$ 179,083
Weighted average interest rate, 2015 retirements	2.38%
Weighted average interest rate, 2016 retirements	2.45%
Weighted average interest rate, 2017 retirements	3.47%
Weighted average interest rate, 2018 retirements	2.60%
Weighted average interest rate, 2019 retirements	3.36%
Weighted average interest rate, thereafter	2.59%
Total long-term borrowings, Weighted-Average Rate	3.25%	3.12%