Inventories - Schedule of Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Public Utilities, Inventory
Total inventories	$ 20,629	$ 20,629	$ 89,661	$ 16,215	$ 16,215
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories		7,490	78,950		5,366
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories		$ 13,139	$ 10,711		$ 10,849