Fair Value of Financial Instruments (Cost and Equity Investees) (Narrative) (Details)		3 Months Ended					9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2014
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, cumulative undistributed earnings	$ 10,600,000	$ 10,600,000					$ 10,600,000
Equity in earnings (losses) of unconsolidated affiliates		7,399,000			$ (6,000)		15,105,000	$ 3,549,000
Unrealized gains (losses) on equity investee activity, net of tax		808,000			(345,000)		(1,287,000)	(12,932,000)
Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 189,100,000	$ 189,100,000					$ 189,100,000		$ 314,300,000
Equity Investees [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Construction projects, percentage complete	100.00%	100.00%					100.00%
Investee [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures										2
Investee [Member] | Pacer [Member] | Canadian Dollars [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates						$ 3,600,000
Revenue, related parties						$ 600,000
Net investment, equity investments	$ 14,800,000	$ 14,800,000					$ 14,800,000		31,400,000
Other equity investment, proceeds related to ongoing liquidation				$ 12,100,000
Income (expense) from investment, change in expected recovery amounts			$ (5,800,000)
Investee [Member] | Pacer [Member] | Canadian Dollars [Member] | Equity Investments, Remaining Amounts Committed [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Contractual joint venture, additional amounts committed	0	0					0
CCI [Member] | Immediate Family Member of Management or Principal Owner [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Cost method investment, original cost	$ 15,000,000	$ 15,000,000					$ 15,000,000
Waha JVs [Member] | Equity Investees [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of pipelines in operation	2	2					2
Equity investment, equity and other contributions		$ 0					$ 73,300,000
Revenue, related parties		3,600,000			80,900,000		255,200,000	142,800,000
Receivables, including retainage, net of BIEC, related parties	$ 52,200,000	52,200,000					52,200,000		71,200,000
Net investment, equity investments	115,000,000	115,000,000					115,000,000		6,000,000
Waha JVs [Member] | Equity Investees [Member] | Interest Rate Swap [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Unrealized gains (losses) on equity investee activity		1,300,000			(600,000)		(2,100,000)	(21,100,000)
Unrealized gains (losses) on equity investee activity, net of tax		800,000			$ (300,000)		(1,300,000)	$ (12,900,000)
Waha JVs [Member] | Equity Investees [Member] | Other [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates		7,400,000					15,100,000
Waha JVs [Member] | Equity Investees [Member] | Credit Facility [Member] | Financial Standby [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 19,000,000	19,000,000					$ 19,000,000		$ 91,000,000
Joint Venture Liquidated in 2016 [Member] | Investee [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures									1
Pensare [Member] | Chief Executive Officer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Payment to acquire cost method investment and warrants		$ 2,000,000
Cost method investment, ownership percentage	4.00%	4.00%					4.00%
Warrants, exercise price (in dollars per share) | $ / shares	$ 11.50
Pensare [Member] | Chief Executive Officer [Member] | Warrant [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Warrants, number held	2,000,000	2,000,000					2,000,000
Common Stock [Member] | Pensare [Member] | Chief Executive Officer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Investment, restriction period (in years)	1 year