Goodwill and Other Intangible Assets (2017 Acquisition) (Narrative) (Details) - April 2017 Acquisition [Member] - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Apr. 30, 2017	Jun. 30, 2017	Apr. 01, 2017
Business Combination [Line Items]
Business combinations, effective date		Apr. 01, 2017
Business combinations, description of acquired entity		a leading wireline/fiber deployment construction contractor with operations in several western states, predominantly servicing cable system operators
Business combinations, payments in cash (in dollars)	$ 38.2
Earn-Out Arrangements [Member]
Business Combination [Line Items]
Business combinations, contingent consideration, earn-out period (in years)		5 years
Business combinations, contingent consideration, fair value of earn-out (in dollars)			$ 25.0