Pension Plans and Other Postretirement Benefits (Details 3) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total		$ 27,245	$ 31,099
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		13,720	15,591
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	10,844	12,718
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	2,681	2,790
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		0	0
Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		0	0
Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	0	0
Level 1 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	0	0
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		27,245	31,099
Level 2 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		13,720	15,591
Level 2 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	10,844	12,718
Level 2 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	2,681	2,790
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		0	0
Level 3 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total		0	0
Level 3 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	0	0
Level 3 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	$ 0	$ 0

[1] None of the trust fund assets for the defined benefit pension plan have been invested in shares of HMEC’s common stock.