Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 1,159,077	$ 755,103
Less accumulated amortization and depreciation	460,955	345,085
Property, plant and equipment, net	698,122	410,018
Land [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	13,057	4,181
Building and Structures [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 115,960	108,341
Building and Structures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Building and Structures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years
Cable and Wire [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 235,471	214,721
Cable and Wire [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	4 years
Cable and Wire [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years
Equipment and Software [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 720,830	391,260
Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	16 years 8 months 12 days
Plant in Service [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 1,085,318	718,503
Plant under Construction [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 73,759	$ 36,600