Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 1,281,387	$ 1,159,077
Less accumulated amortization and depreciation	595,060	460,955
Property, plant and equipment, net	686,327	698,122
Depreciation	151,063	123,995	$ 69,287
Capital lease agreements	5,900
Unamortized capitalized software costs	28,000	15,700
Land [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	6,418	13,057
Building and Structures [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 195,540	115,960
Building and Structures [Member] | Minimum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	10 years
Building and Structures [Member] | Maximum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	40 years
Cable and Wire [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 286,999	235,471
Cable and Wire [Member] | Minimum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	4 years
Cable and Wire [Member] | Maximum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	40 years
Equipment and Software [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 730,228	720,830
Equipment and Software [Member] | Minimum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	2 years
Equipment and Software [Member] | Maximum [Member]
Property, plant and equipment [Abstract]
Estimated useful lives	16 years 8 months 12 days
Plant In Service [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 1,219,185	1,085,318
Plant Under Construction [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 62,202	$ 73,759