Income taxes (Tables)

12 Months Ended

Dec. 31, 2011

Income taxes

Components of income taxes attributable to net income for common stock

Years ended December 31	2011		2010		2009
(in thousands)
Federal
Current	$ (7,638	)	$(25,446	)	$25,691
Deferred	73,494		85,268		14,161
Deferred tax credits, net	—		(901	)	(593	)
	65,856		58,921		39,259
State
Current	2,437		(7,392	)	6,930
Deferred	5,949		13,425		(783	)
Deferred tax credits, net	1,690		2,868		(1,483	)
	10,076		8,901		4,664
Total	$ 75,932		$ 67,822		$43,923

Schedule of reconciliation of amount of income taxes computed at federal statutory rate

Years ended December 31	2011		2010		2009
(in thousands)
Amount at the federal statutory income tax rate	$75,618		$64,136		$45,088
Increase (decrease) resulting from:
State income taxes, net of federal income tax benefit	6,550		5,786		3,033
Other, net	(6,236	)	(2,100	)	(4,198	)
Total	$75,932		$67,822		$43,923
Effective income tax rate	35.1	%	37.0	%	34.1%

Schedule of deferred tax assets and liabilities

December 31	2011	2010
(in thousands)
Deferred tax assets
Allowance for loan losses	$  14,076	$  16,461
Retirement benefits	6,175	–
Other	33,217	35,878
	53,468	52,339
Deferred tax liabilities
Property, plant and equipment related	255,488	188,490
Retirement benefits	–	2,479
Goodwill	22,028	20,130
Regulatory assets, excluding amounts attributable to property, plant and equipment	32,343	32,074
FHLB stock dividend	20,552	20,552
Change in accounting method related to repairs	48,566	46,702
Other	28,542	20,870
	407,519	331,297
Net deferred income tax liability	$354,051	$278,958

Schedule of changes in total unrecognized tax benefits

(in millions)	2011		2010		2009
Unrecognized tax benefits, January 1	$ 15.4		$ 26.5		$ 27.9
Additions based on tax positions taken during the year	–		11.0		–
Reductions based on tax positions taken during the year	(0.6	)	–		–
Additions for tax positions of prior years	0.1		2.2		0.4
Reductions for tax positions of prior years	(8.1	)	(18.2	)	(1.8	)
Settlements	–		(6.1	)	–
Lapses of statute of limitations	(1.1	)	–		–
Unrecognized tax benefits, December 31	$  5.7		$ 15.4		$ 26.5