Income Tax (tables)

3 Months Ended

Mar. 31, 2013

Income Tax Expense (Benefit) [Abstract]

Effective Tax Rate Reconciliation

	March 31,
	2013		2012
Federal statutory tax rate	35.0	%	35.0	%
Increase (decrease):
Current state income tax, net of federal tax benefit	4.7		4.6
Amortization of investment and energy tax credits	(0.3	)	(0.3	)
Differences required to be flowed-through by regulatory commissions	2.4		1.6
Gains on company and trust-owned life insurance	(0.3	)	(0.4	)
Other, net	(0.7	)	0.2
Effective income tax rate	40.8	%	40.7	%