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Employee Benefit Plans (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014
Eighth District Electrical Pension Fund [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans, Collective-Bargaining Arrangement, Percentage of Employer's Contributions				5.00%		5.00%		5.00%
IBEW Local 1249 Pension Plan [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans, Collective-Bargaining Arrangement, Percentage of Employer's Contributions		5.00%	5.00%
IBEW Local 769 Management Pension Plan [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans, Collective-Bargaining Arrangement, Percentage of Employer's Contributions					5.00%		5.00%
Multiemployer Plans, Pension [Member]
Defined Contribution Plans [Line Items]
Number Of Locals Covered Under Multiemployer Defined Plans	100
Multiemployer Plans, Pension [Member] | Maximum [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans Red Zone Funded Status Percentage	65.00%
Multiemployer Plans Yellow Zone Funded Status Percentage	80.00%
Multiemployer Plans, Pension [Member] | Minimum [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans Green Zone Funded Status Percentage	80.00%
Multiemployer Plans Yellow Zone Funded Status Percentage	65.00%
Employee Benefit Plan [Member]
Defined Contribution Plans [Line Items]
Defined Contribution Plan, Cost Recognized	$ 0.6	$ 0.7	$ 0.6
Profit Sharing and Thrift Employee Benefit Plan [Member]
Defined Contribution Plans [Line Items]
Defined Contribution Plan, Cost Recognized	$ 4.6	$ 3.4	$ 6.9

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- References

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Represents the percentage funded for green zone status.

+ References

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Represents the percentage funded for red zone status.

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Represents the percentage funded for yellow zone status.

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Represents information pertaining to number of locals covered under multiemployer defined plan.

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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- Definition

Percentage of contributions required by a collective bargaining arrangement to all contributions required of an employer related to a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

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