Pension Plans and Other Postretirement Benefits (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Amortization of:
Total recognized in other comprehensive income (loss)	$ 1,810		$ (5,645)		$ (1,276)
Weighted-average assumptions used to determine expense:
Discount rate	4.46%		3.51%		2.95%
Expected return on plan assets		[1]		[1]		[1]
Weighted-average assumptions used to determine benefit obligations as of December 31:
Discount rate	3.66%		4.46%		3.51%
Expected return on plan assets		[1]		[1]		[1]
Defined Benefit Plan [Member]
Service Cost
Benefit accrual	0		0		0
Other expenses	360		360		360
Interest cost	1,679		1,369		1,427
Expected return on plan assets	(2,402)		(2,238)		(2,423)
Settlement loss	2,668		867		1,209
Amortization of:
Prior service cost	0		0		0
Actuarial loss	1,371		1,602		2,367
Net periodic pension expense	3,676		1,960		2,940
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost	0		0		0
Net actuarial loss	(1,037)		(1,888)		115
Amortization of:
Prior service cost	0		0		0
Actuarial loss	(1,371)		(1,602)		(2,367)
Total recognized in other comprehensive income (loss)	(2,408)		(3,490)		(2,252)
Weighted-average assumptions used to determine expense:
Discount rate	4.46%		3.51%		3.66%
Expected return on plan assets	7.50%		7.50%		7.50%
Annual rate of salary increase		[1]		[1]		[1]
Weighted-average assumptions used to determine benefit obligations as of December 31:
Discount rate	3.66%		4.46%		3.51%
Expected return on plan assets	7.50%		7.50%		7.50%
Annual rate of salary increase		[1]		[1]		[1]
Supplemental Defined Benefit Plans [Member]
Service Cost
Benefit accrual	0		0		0
Other expenses	0		0		0
Interest cost	716		616		676
Expected return on plan assets	0		0		0
Settlement loss	0		0		0
Amortization of:
Prior service cost	0		124		124
Actuarial loss	157		203		171
Net periodic pension expense	873		943		971
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost	0		0		0
Net actuarial loss	2,431		(783)		817
Amortization of:
Prior service cost	(2)		(124)		(124)
Actuarial loss	(157)		(203)		(171)
Total recognized in other comprehensive income (loss)	$ 2,272		$ (1,110)		$ 522
Weighted-average assumptions used to determine expense:
Discount rate	4.46%		3.51%		3.86%
Expected return on plan assets		[1]		[1]		[1]
Annual rate of salary increase		[1]		[1]		[1]
Weighted-average assumptions used to determine benefit obligations as of December 31:
Discount rate	3.66%		4.46%		3.51%
Expected return on plan assets		[1]		[1]		[1]
Annual rate of salary increase		[1]		[1]		[1]

[1] Not applicable.