Rate Matters (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Rate Matters [Abstract]
Authorized percentage increase in annual revenue by PPUC (in hundredths)	8.70%
Authorized dollar increase in annual revenue by PPUC	$ 3,400
Distribution system improvement charge percentage over base rate	5.00%
Distribution system improvement charge revenue	$ 328	$ 0