Pension Plans and Other Postretirement Benefits (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan [Member]
Summary of minimum funding requirement and the expected full year contributions for the Company's plans
Minimum funding requirement for 2015	$ 0
Expected contributions (approximations) for the year ended December 31, 2015 as of the time of this Form 10-K	0	[1]
Supplemental Defined Benefit Plans [Member]
Summary of minimum funding requirement and the expected full year contributions for the Company's plans
Expected contributions (approximations) for the year ended December 31, 2015 as of the time of this Form 10-K	$ 1,320	[1]

[1] HMEC’s Annual Report on Form 10-K for the year ended December 31, 2014.