Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies - Agreement with Southern California Gas Company (Details)

v2.4.0.6
Summary of significant accounting policies - Agreement with Southern California Gas Company (Details) (USD $)
0 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Jun. 13, 2011
Common stock
Class of Stock [Line Items]      
Redeemable common stock $ 0 $ 0 $ 500,000
Redeemable common stock, redemption right maximum period     5 years