Income Tax (tables)

9 Months Ended

Sep. 30, 2012

Income Tax Expense (Benefit) [Abstract]

Effective Tax Rate Reconciliation

	September 30,
	2012		2011
Federal statutory tax rate	35.0	%	35.0	%
Increase (decrease):
Current state income tax, net of federal tax benefit	4.7	%	4.5	%
Amortization of investment and energy tax credits	(0.3	)%	(0.4	)%
Differences required to be flowed-through by regulatory commissions	1.4	%	1.5	%
Gains on company and trust-owned life insurance	(1.2	)%	(0.9	)%
One-time state tax adjustment, net of federal benefit	4.7	%	—	%
Other - net	0.7	%	0.7	%
Effective income tax rate	45.0	%	40.4	%