Significant Accounting Policies (Narrative) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Sep. 07, 2012
Accounts receivable	$ 48,159,043	$ 46,650,901
Fuel stock	8,857,008	9,466,767
Marketable securities	10,254,243	10,158,016	10,000,000
Marketable securities, fair value	10,300,000	10,100,000
ML&P for South Central Power Project Costs [Member]
Accounts receivable	400,000	3,000,000
Alaska Energy Authority For Grant [Member]
Accounts receivable	$ 7,500,000	$ 4,000,000