Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plans
Components of net periodic benefit cost:
Service cost	$ 0	$ 1,621	$ 0	$ 3,256
Interest cost	204	1,404	408	2,817
Expected long-term return on assets	0	(1,449)	0	(2,909)
Actuarial gain	184	1,407	369	2,819
Prior service cost amortization	0	57	0	114
Settlement charge	701	115	3,363	3,673
Net periodic (income) expense	1,089	3,155	4,140	9,770
Postretirement Benefit Plans
Components of net periodic benefit cost:
Service cost	98	59	196	119
Interest cost	117	224	233	450
Expected long-term return on assets	(114)	(383)	(229)	(770)
Actuarial gain	0	(209)	0	(421)
Transition amortization	0	15	0	30
Net periodic (income) expense	$ 101	$ (294)	$ 200	$ (592)