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Business and Organization - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified |
3 Months Ended | 6 Months Ended | 12 Months Ended | 1 Months Ended | 6 Months Ended | ||||
|---|---|---|---|---|---|---|---|---|---|
|
Jun. 30, 2013
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Jun. 30, 2012
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Jun. 30, 2013
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Jun. 30, 2012
|
Dec. 31, 2012
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Jul. 31, 2013
Subsequent Event [Member]
Entity
|
Jun. 30, 2012
Electric Power Division [Member]
United States [Member]
Entity
|
Jun. 30, 2012
Electric Power Division [Member]
Canada [Member]
Entity
|
Jun. 30, 2012
Natural Gas and Pipeline Division [Member]
United States [Member]
Entity
|
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| Organization And Description Of Business [Line Items] | |||||||||
| Fiber Optic Licensing Terms, Minimum in years | 5 years | 5 years | 5 years | 5 years | 5 years | ||||
| Fiber Optic Licensing Terms, Maximum in years | 25 years | 25 years | 25 years | 25 years | 25 years | ||||
| Number of business acquisitions | 2 | 2 | 1 | 1 | |||||
| Cash paid for acquisition | $ 57.5 | $ 118.0 | |||||||
| Number of shares issued for acquisition of company | 1,927,113 | 763,272 | |||||||
| Common stock value | 37.3 | 18.7 | |||||||
| Payment of cash to repay acquiree debt | 11.0 | ||||||||
| Proceeds from sale of subsidiary | $ 265.0 | ||||||||