Derivative Financial Instruments Derivative Financial Instruments (Schedule of NGL Derivative Contracts Volume and Weighted Average Prices) (Details)	Jun. 30, 2017 bbl / d MMBTU / d $ / MMBTU $ / bbl
NGL contract, in BBLS [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	2,500
NGL contract, MMBtu Equivalent [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU / d	6,920
Butane [Member] | NGL contract, in BBLS [Member] | Collar Contracts With Short Puts For Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	2,000
Butane [Member] | NGL contract, in BBLS [Member] | Collar Contracts With Short Puts For Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	0
Butane [Member] | NGL contract, in BBLS [Member] | Collar Contracts With Short Puts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	0
Butane [Member] | NGL contract, in BBLS [Member] | Collar Contracts With Short Puts for Year 3 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	0
Butane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts With Short Puts For Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Average Cap Price	36.12
Derivative, Average Floor Price	29.25
Derivative, Notional Amount, Price Per Unit	23.40
Butane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts With Short Puts For Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Average Cap Price	0.00
Derivative, Average Floor Price	0.00
Derivative, Notional Amount, Price Per Unit	0.00
Butane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts With Short Puts for Year 2 [Member]
Derivative [Line Items]
Derivative, Average Cap Price	0.00
Derivative, Average Floor Price	0.00
Derivative, Notional Amount, Price Per Unit	0.00
Butane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts With Short Puts for Year 3 [Member]
Derivative [Line Items]
Derivative, Average Cap Price	0.00
Derivative, Average Floor Price	0.00
Derivative, Notional Amount, Price Per Unit	0.00
Ethane [Member] | NGL contract, in BBLS [Member] | Collar Contract For Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	3,000
Ethane [Member] | NGL contract, in BBLS [Member] | Collar Contract For Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	3,000
Ethane [Member] | NGL contract, in BBLS [Member] | Collar Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	0
Ethane [Member] | NGL contract, in BBLS [Member] | Collar Contracts for Year 3 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	0
Ethane [Member] | NGL contracts, price per BBL [Member] | Collar Contract For Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Average Cap Price	11.83
Derivative, Average Floor Price	8.68
Ethane [Member] | NGL contracts, price per BBL [Member] | Collar Contract For Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Average Cap Price	11.83
Derivative, Average Floor Price	8.68
Ethane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Average Cap Price	0.00
Derivative, Average Floor Price	0.00
Ethane [Member] | NGL contracts, price per BBL [Member] | Collar Contracts for Year 3 [Member]
Derivative [Line Items]
Derivative, Average Cap Price	0.00
Derivative, Average Floor Price	0.00
Ethane [Member] | NGL contract, MMBtu Equivalent [Member] | Basis Swap Contracts for Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU / d	6,920
Ethane [Member] | NGL contract, MMBtu Equivalent [Member] | Basis Swap Contracts for Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU / d	6,920
Ethane [Member] | NGL contract, MMBtu Equivalent [Member] | Basis Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU / d	6,920
Ethane [Member] | NGL contract, MMBtu Equivalent [Member] | Basis Swap Contracts for Year 3 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU / d	6,920
Ethane [Member] | NGL contract, price per MMBtu Equivalent [Member] | Basis Swap Contracts for Third Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / MMBTU	1.60
Ethane [Member] | NGL contract, price per MMBtu Equivalent [Member] | Basis Swap Contracts for Fourth Quarter of Year One [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / MMBTU	1.60
Ethane [Member] | NGL contract, price per MMBtu Equivalent [Member] | Basis Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / MMBTU	1.60
Ethane [Member] | NGL contract, price per MMBtu Equivalent [Member] | Basis Swap Contracts for Year 3 [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / MMBTU	1.60