Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of Multiemployer Plans [Table Text Block]

Information in the table has been presented separately for individually significant plans and in the aggregate for all other plans.  

Pension Fund	EIN/Pension Plan Number		Pension Protection Act Zone Status								Contributions to Plan for the Year Ended December 31,						Funding Plan		Surcharge Imposed
			Status		Plan Year End		Status		Plan Year End		2015		2014		2013
											(in thousands)
Defined Benefit Plans:
National Electrical Benefit Fund		53-0181657 001		Green		12/31/2014		Green		12/31/2013	$	6,930	$	6,330	$	6,048		No		No
Eighth District Electrical Management Pension Fund		84-6100393 001		Green		3/31/2015		Green		3/31/2014		5,598		5,197		5,672		No		No
IBEW Local 769 Management Pension Plan		86-6049763 001		Green		6/30/2014		Green		6/30/2013		2,120		1,833		1,291		No		No
IBEW Local 1249 Pension Plan		15-6035161 001		Yellow		12/31/2014		Yellow		12/31/2013		2,042		2,103		3,147		Yes		No
Defined Contribution Plans:
National Electrical Annuity Plan		52-6132372 001				n/a				n/a		24,226		20,694		21,002		n/a		n/a
Eighth District Electrical Pension Fund Annuity Plan		84-6100393 002				n/a				n/a		3,700		3,553		2,427		n/a		n/a
All other plans:												8,070		5,114		4,300
Total Contributions:											$	52,686	$	44,824	$	43,887