Pension Plans and Other Postretirement Benefits (Details 2) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amortization of:
Total recognized in other comprehensive income (loss)		$ 37	$ (1,815)	$ 1,810
Weighted average assumptions used to determine expense:
Discount rate				4.46%
Expected return on plan assets	[1]			0.00%
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate				3.66%
Expected return on plan assets	[1]			0.00%
Defined Benefit Plan [Member]
Service cost:
Benefit accrual		0	0	$ 0
Other expenses		650	450	360
Interest cost		1,244	1,189	1,679
Expected return on plan assets		(1,675)	(1,875)	(2,402)
Settlement loss		0	0	2,668
Amortization of:
Prior service cost		0	0	0
Actuarial loss		393	1,626	1,371
Net periodic pension expense		612	1,390	3,676
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost		0	0	0
Net actuarial loss (gain)		175	930	(1,037)
Amortization of:
Prior service cost		0	0	0
Actuarial loss		(393)	(1,626)	(1,371)
Total recognized in other comprehensive income (loss)		$ (218)	$ (696)	$ (2,408)
Weighted average assumptions used to determine expense:
Discount rate		4.20%	3.66%	4.46%
Expected return on plan assets		6.50%	6.75%	7.50%
Annual rate of salary increase	[1]
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate		3.90%	4.20%	3.66%
Expected return on plan assets		6.50%	6.75%	7.50%
Annual rate of salary increase	[1]
Supplemental Defined Benefit Plans [Member]
Service cost:
Benefit accrual		$ 0	$ 0	$ 0
Other expenses		0	0	0
Interest cost		687	654	716
Expected return on plan assets		0	0	0
Settlement loss		0	0	0
Amortization of:
Prior service cost		0	0	0
Actuarial loss		233	273	157
Net periodic pension expense		920	927	873
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost		0	0	0
Net actuarial loss (gain)		488	(845)	2,431
Amortization of:
Prior service cost		0	0	(2)
Actuarial loss		(233)	(273)	(157)
Total recognized in other comprehensive income (loss)		$ 255	$ (1,118)	$ 2,272
Weighted average assumptions used to determine expense:
Discount rate		4.20%	3.66%	4.46%
Expected return on plan assets	[1]	6.50%
Annual rate of salary increase	[1]
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate		3.90%	4.20%	3.66%
Expected return on plan assets	[1]	6.50%
Annual rate of salary increase	[1]

[1] Not applicable.