Pension Plans and Other Postretirement Benefits (Details 2) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
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 2013	$ 0
Contributions made in the six months ended June 30, 2013	0
Expected contributions (approximations) for the year ended December 31, 2013 as of the time of:
This Form 10-Q (1)	3,000	[1]
2012 Form 10-K (2)	2,500	[2]
Supplemental Defined Benefit Plans [Member]
Summary of minimum funding requirement, contributions made and the expected full year contributions for the Company's plans
Minimum funding requirement for 2013	0
Contributions made in the six months ended June 30, 2013	656
Expected contributions (approximations) for the year ended December 31, 2013 as of the time of:
This Form 10-Q (1)	1,320	[1]
2012 Form 10-K (2)	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
Minimum funding requirement for 2013	0
Contributions made in the six months ended June 30, 2013	215
Expected contributions (approximations) for the year ended December 31, 2013 as of the time of:
This Form 10-Q (1)	480	[1]
2012 Form 10-K (2)	$ 480	[2]

[1] HMEC’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2013.

[2] HMEC’s Annual Report on Form 10-K for the year ended December 31, 2012, specifically “Notes to Consolidated Financial Statements — Note 9 — Pension Plans and Other Postretirement Benefits”.