Inventories - Narrative (Details) (USD $) In Millions, unless otherwise specified			0 Months Ended
	Jun. 30, 2014 ft3 Storage_Agreement	Sep. 30, 2013 ft3	Jun. 30, 2014 Minimum	Jun. 30, 2014 Maximum
Inventory
Number of Storage Agreements	3
SCAA Contract Term, in years			1 year	3 years
Volume of gas storage inventories released under SCAAs with non-affiliates (in cubic feet)	2,100,000,000	600,000,000
Carrying value of gas storage inventories released under SCAAs with non-affiliates	$ 8.9	$ 2.4