Pension Plans and Other Postretirement Benefits (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Defined Benefit Plan [Member]
Summary of minimum funding requirement, contributions made and the expected full year contributions for the Company's plans
Minimum funding requirement for 2014	$ 0
Contributions made in the three months ended March 31, 2014	0
Expected contributions (approximations) for the year ended December 31, 2014 as of the time of :
This Form 10-Q	2,000	[1]
2013 Form 10-K	2,000	[2]
Supplemental Defined Benefit Plans [Member]
Summary of minimum funding requirement, contributions made and the expected full year contributions for the Company's plans
Contributions made in the three months ended March 31, 2014	332
Expected contributions (approximations) for the year ended December 31, 2014 as of the time of :
This Form 10-Q	1,320	[1]
2013 Form 10-K	1,320	[2]
Other Postretirement Benefits [Member]
Summary of minimum funding requirement, contributions made and the expected full year contributions for the Company's plans
Contributions made in the three months ended March 31, 2014	60
Expected contributions (approximations) for the year ended December 31, 2014 as of the time of :
This Form 10-Q	217	[1]
2013 Form 10-K	$ 217	[2]

[1] HMEC’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2014.

[2] HMEC’s Annual Report on Form 10-K for the year ended December 31, 2013, specifically “Notes to Consolidated Financial Statements — Note 9 — Pension Plans and Other Postretirement Benefits”.