Fair Value of Financial Instruments (Cost and Equity Investees) (Narrative) (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Unrecognized unrealized fair market value losses, net of tax	$ 345,000		$ 0	$ 12,932,000	$ 0
Net investment in equity investees, liability	98,415,000			98,415,000		$ 68,119,000
Equity investees, earnings related to increases in expected recoveries	(6,000)		(371,000)	3,549,000	(3,594,000)
Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	280,600,000			280,600,000		292,800,000
Immediate Family Member of Management or Principal Owner [Member] | Cost Investment [Member] | CCP [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Cost method investment, original cost	$ 15,000,000			$ 15,000,000
Equity Investees [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures	2			2
Construction projects, percentage complete	100.00%			100.00%
Equity Investees [Member] | Pacer [Member] | Canadian Dollars [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Aggregate net carrying value, joint ventures	$ 32,200,000			$ 32,200,000		28,800,000
Equity Investees [Member] | Pacer [Member] | Canadian Dollars [Member] | Capital Support Agreement [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investees, earnings related to increases in expected recoveries		$ 3,600,000
Equity Investees [Member] | Waha JVs [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Revenue, related parties	80,900,000			142,800,000
Receivables, net of billings in excess of costs, related parties	11,400,000			11,400,000
Net investment in equity investees, liability	21,900,000			21,900,000		4,400,000
Equity 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	600,000			21,100,000
Unrecognized unrealized fair market value losses, net of tax	300,000			12,900,000
Equity 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	$ 109,000,000			$ 109,000,000		$ 78,000,000
Equity Investees [Member] | Joint Venture Liquidated in 2016 [Member] | Pacer [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures	1			1
Joint Venture [Member] | Pacer [Member] | Canadian Dollars [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Revenue, related parties	$ 200,000		$ 300,000	$ 800,000	$ 1,800,000
Joint Venture [Member] | Pacer [Member] | Canadian Dollars [Member] | Capital Support Agreement [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Contractual joint venture, additional amounts committed	$ 0			$ 0