Segments and Related Information (Schedule of Significant Customers, Revenue Concentration Information) (Details) - Customer Concentration Risk [Member] - Revenue [Member]		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
AT&T (including DIRECTV) [Member]
Revenue, Significant Customers [Line Items]
Concentration risk, percentage of total	[1]	23.00%	27.00%
Energy Transfer Affiliates [Member]
Revenue, Significant Customers [Line Items]
Concentration risk, percentage of total	[2]	6.00%	26.00%

[1] The Company’s relationship with AT&T is based upon multiple separate master service and other service agreements, including for installation and maintenance services, as well as construction/installation contracts for AT&T’s: (i) wireless business; (ii) wireline/fiber businesses; and (iii) various install-to-the-home businesses, including DIRECTV®. Revenue from AT&T is included in the Communications segment.

[2] The Company's relationship with Energy Transfer affiliates is based upon various construction contracts for pipeline activities with Energy Transfer Partners L.P., and its subsidiaries and affiliates, all of which are consolidated by Energy Transfer Equity, L.P. Revenue from Energy Transfer affiliates is included in the Oil and Gas segment.