Pension Plans and Other Postretirement Benefits (Details 6) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2014		Dec. 31, 2013
Accumulated postretirement benefit obligations and Service and interest cost components of the net periodic postretirement benefit expense
Accumulated postretirement benefit obligations Effect of a one percentage point increase		$ 0	[1]	$ 0
Accumulated postretirement benefit obligations Effect of a one percentage point decrease		0	[1]	0
Service and interest cost components of the net periodic postretirement benefit expense Effect of a one percentage point increase		0	[1]	2
Service and interest cost components of the net periodic postretirement benefit expense Effect of a one percentage point decrease		$ 0	[1]	$ (2)
Weighted-average assumptions used to determine benefit obligations as of December 31:
Discount rate		3.66%		4.46%
Healthcare cost trend rate	[1]	0		0
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)	[1]	0		0
Year the rate is assumed to reach the ultimate trend rate	[1]
Expected return on plan assets	[1]	0		0
Weighted-average assumptions used to determine net periodic benefit cost for the years ended December 31:
Discount rate		4.46%		3.51%
Healthcare cost trend rate		0.00%	[1]	7.50%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)		0.00%	[1]	5.00%
Year the rate is assumed to reach the ultimate trend rate				2022
Expected return on plan assets	[1]	0.00%		0.00%

[1] Not applicable.