Fair Value of Financial Instruments (Cost and Equity Method Investments) (Narrative) (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2017	Dec. 31, 2015
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Unrecognized unrealized fair market value losses, net of tax	$ 4,577,000		$ 0	$ 12,587,000	$ 0
Net investment in equity method investments, liabilities	90,482,000			90,482,000			$ 68,119,000
Equity method investments, earnings related to expected recoveries	489,000		$ (2,638,000)	3,555,000	$ (3,223,000)
Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	337,800,000			337,800,000			292,800,000
Equity Method Investees [Member] | Waha JVs [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Revenue, related parties	51,600,000			61,900,000
Receivables, net of billings in excess of costs, related parties	34,500,000			34,500,000
Net investment in equity method investments, liabilities	19,200,000			19,200,000			4,400,000
Equity Method Investees [Member] | Waha JVs [Member] | Interest Rate Swaps [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Unrecognized unrealized fair market value losses, before tax	7,500,000			20,500,000
Unrecognized unrealized fair market value losses, net of tax	4,600,000			12,600,000
Equity Method Investees [Member] | Waha JVs [Member] | Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	78,000,000			78,000,000			86,000,000
Equity Method Investees [Member] | Waha JVs [Member] | Credit Facility [Member] | Financial Standby [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 78,000,000			$ 78,000,000
Equity Method Investees [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures	2			2
Aggregate net carrying value, joint ventures	$ 33,100,000			$ 33,100,000			$ 28,800,000
Equity Method Investees [Member] | Pacer [Member] | Canadian Dollars [Member] | Forecast [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Amounts expected to be advanced, related parties						$ 0
Equity Method Investees [Member] | Pacer [Member] | Canadian Dollars [Member] | Capital Support Agreement [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, earnings related to expected recoveries		$ 3,600,000
Equity Method Investees [Member] | Pacer [Member] | Performance Guarantees [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Construction projects, percentage complete	100.00%			100.00%
Immediate Family Member of Management or Principal Owner [Member] | Cost Method Investment [Member] | Cross Country Pipeline Supply, Inc. [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Cost method investment, original cost	$ 15,000,000			$ 15,000,000