Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined pension plan benefits
Components of net periodic benefit cost
Service cost – benefits earned during the year	$ 8	$ 15	$ 22	$ 47
Interest cost on projected benefit obligations	450	496	1,350	1,489
Expected return on plan assets	(538)	(703)	(1,614)	(2,110)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	177	174	532	521
Settlement expense	0	680	0	680
Net periodic benefit cost	97	662	290	627
Other postretirement benefits
Components of net periodic benefit cost
Service cost – benefits earned during the year	36	32	110	97
Interest cost on projected benefit obligations	62	67	188	202
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	14	41	40	121
Amortization of net loss	0	0	0	0
Settlement expense	0	0	0	0
Net periodic benefit cost	$ 112	$ 140	$ 338	$ 420