Federal and State Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Tax Expense (Benefit) [Abstract]

Summary of consolidated income tax expense

	Years ended
(Dollars in thousands)	December 31, 2012		December 31, 2011		December 31, 2010
Current
Federal	$	12,718	8,836		3,724
State	5,522		4,191		3,481
Total current tax expense	18,240		13,027		7,205
Deferred
Federal	708		(11,256	)	115
State	129		(2,052	)	23
Total deferred tax expense (benefit)	837		(13,308	)	138
Total income tax expense (benefit)	$	19,077	(281	)	7,343

Summary of Effective Income Tax Rate

	Years ended
	December 31, 2012		December 31, 2011		December 31, 2010
Federal statutory rate	35.0	%	35.0	%	35.0	%
State taxes, net of federal income tax benefit	3.9	%	8.1	%	4.6	%
Tax-exempt interest income	(14.0	)%	(65.5	)%	(17.3	)%
Tax credits	(4.2	)%	(22.1	)%	(7.3	)%
Goodwill impairment charge	—	%	42.3	%	—	%
Other, net	(0.5	)%	0.6	%	(0.2	)%
Effective tax rate	20.2	%	(1.6	)%	14.8	%

Summary of deferred tax assets and deferred tax liabilities

(Dollars in thousands)	December 31, 2012			December 31, 2011
Deferred tax assets
Allowance for loan and lease losses	$	50,963		53,555
Other real estate owned	7,685			7,852
Interest rate swap agreements	6,549			3,465
Federal income tax credits	3,543			2,400
Deferred compensation	3,129			2,964
Impairment of equity securities (FHLMC & FNMA)	2,954			2,954
Employee benefits	2,715			2,610
Non-accrued interest	2,008			2,894
Other	2,446			2,713
Total gross deferred tax assets	81,992			81,407
Deferred tax liabilities
Available-for-sale securities	(37,083		)	(24,783	)
FHLB stock dividends	(10,143		)	(10,165	)
Depreciation of premises and equipment	(5,437		)	(6,169	)
Deferred loan costs	(5,316		)	(4,954	)
Intangibles	(1,832		)	(1,566	)
Other	(1,787		)	(2,689	)
Total gross deferred tax liabilities	(61,598		)	(50,326	)
Net deferred tax asset	$	20,394		31,081

Income Tax returns jurisdictions and years subject to examination

	Years ended December 31,
Federal	2009, 2010 and 2011
Montana	2009, 2010 and 2011
Idaho	2009, 2010 and 2011
Colorado	2008, 2009, 2010 and 2011
Utah	2009, 2010 and 2011