Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Benefits
Components of the net periodic benefit cost
Service cost	$ 0	$ 63	$ 0	$ 118
Interest cost	48	(1,118)	97	91
Expected return on plan assets	0	1,561	0	0
Recognized net actuarial loss	37	388	73	758
Benefit cost (income)	85	894	170	967
Postretirement Benefits
Components of the net periodic benefit cost
Service cost	167	210	380	450
Interest cost	370	386	775	792
Amortization of prior service cost	(89)	(136)	(177)	(272)
Recognized net actuarial loss	149	367	384	759
Benefit cost (income)	$ 597	$ 827	$ 1,362	$ 1,729