Pension - Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Components of net periodic benefit cost:
Interest cost	$ 15	$ 19	$ 29	$ 35
Service cost	6	3	13	13
Expected return on plan assets	(23)	(29)	(46)	(47)
Amortization of prior service costs	2	2	5	5
Amortization of actuarial loss	28	23	56	58
Net periodic benefit cost	$ 28	$ 18	$ 57	$ 64