Employee Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Pension Plan [Member]
Net periodic benefit cost
Service cost	$ 1,303	$ 1,868	$ 2,606	$ 3,150
Interest cost	1,468	1,326	2,936	2,587
Expected return on plan assets	(1,739)	(1,550)	(3,478)	(2,886)
Amortization of net loss	544	1,105	1,088	2,211
Net periodic benefit cost	1,576	2,749	3,152	5,062
Estimated 2014 pension plan contribution, disclosed in prior year 10K					6,260
Contribution by employer			3,315
Postretirement Benefit Plan [Member]
Net periodic benefit cost
Service cost	924	752	1,848	1,505
Interest cost	586	423	1,172	847
Expected return on plan assets	0	0	0	0
Amortization of net loss	224	138	448	274
Net periodic benefit cost	$ 1,734	$ 1,313	$ 3,468	$ 2,626