Income Taxes (Tables)

6 Months Ended

Jun. 30, 2012

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

A reconciliation of the federal statutory income tax rate to the effective income tax rate applicable to income before income tax expense is as follows:

	Three-Month Periods				Six-Month Periods
	Ended June 30,				Ended June 30,
	2012		2011		2012		2011
Federal statutory income tax rate	35	%	35	%	35	%	35	%
Federal and state income tax credits	(14	)	(10	)	(12	)	(10	)
State income tax, net of federal income tax benefit	2		1		2		1
Income tax effect of foreign income	(3	)	(2	)	(3	)	(2	)
Income tax method change	(6	)	—		(2	)	—
Effects of ratemaking	(3	)	(1	)	(3	)	(1	)
Other, net	1		2		1		2
Effective income tax rate	12	%	25	%	18	%	25	%