Summary of Significant Accounting Policies - Significant Estimates Used by Management in Determining Fair Values of Company's Reporting Units (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Electric Power and Oil and Gas Services Divisions [Member]
Goodwill Impairment Testing Assumptions [Line Items]
Years of cash flows before terminal value	5 years	5 years	5 years
Weighting of three approaches:
Discounted cash flows	70.00%	70.00%	70.00%
Market multiple	15.00%	15.00%	15.00%
Market capitalization	15.00%	15.00%	15.00%
Electric Power and Oil and Gas Services Divisions [Member] | Minimum [Member]
Goodwill Impairment Testing Assumptions [Line Items]
Discount rates	12.00%	12.00%	12.00%
EBITDA multiples	5.0	5.0	4.5
Electric Power and Oil and Gas Services Divisions [Member] | Maximum [Member]
Goodwill Impairment Testing Assumptions [Line Items]
Discount rates	14.00%	14.00%	13.00%
EBITDA multiples	6.0	8.0	8.0
Fiber Optic Licensing Division [Member]
Goodwill Impairment Testing Assumptions [Line Items]
Years of cash flows before terminal value	15 years	15 years	15 years
Discount rates	12.00%	12.00%	12.00%
EBITDA multiples	9.5	9.5	9.5
Weighting of three approaches:
Discounted cash flows	90.00%	90.00%	90.00%
Market multiple	5.00%	5.00%	5.00%
Market capitalization	5.00%	5.00%	5.00%