Related Party Transactions - Coronado Midstream (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Related Party Transaction
Natural gas revenue from related party	$ 4,089	$ 1,043	$ 6,416	$ 1,726
Coronado Midstream
Related Party Transaction
Initial term of the additional shared services agreement			10 years
Agreement termination, written notice period			30 days
Natural gas revenue from related party	6,505	1,723	10,412	2,818
Amount owed from related party from the sale of gas, gas products and residue gas	$ 3,310		$ 3,310		$ 1,303
Coronado Midstream | Coronado Midstream Plant
Related Party Transaction
Percent of natural gas revenue from related party	87.00%		87.00%
Coronado Midstream | Chevron Headlee Plant
Related Party Transaction
Percent of natural gas revenue from related party	94.56%		94.56%