Employee Benefit Plans (Components of Net Periodic Postretirement Benefit Cost) (Details) (Other postretirement benefits, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other postretirement benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost — benefits earned during the year	$ 130	$ 154	$ 143
Interest cost on projected benefit obligations	269	255	295
Amortization of prior service cost	161	161	161
Net periodic pension cost	$ 560	$ 570	$ 599