Employee Benefit Plans (Components of Net Periodic Postretirement Benefit Cost) (Details) - Other postretirement benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost — benefits earned during the year	$ 147	$ 130	$ 154
Interest cost on projected benefit obligations	251	269	255
Amortization of prior service cost	53	161	161
Net periodic pension cost	$ 451	$ 560	$ 570