Income Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Income tax expense is comprised of the following:

	Years Ended December 31,
	2011			2010		2009
Taxes currently payable
Federal	$	45,026		$	5,188	$	18,291
State	1,823			1,460		237
Deferred (benefit) expense	(756		)	30,443		7,117
	$	46,093		$	37,091	$	25,645

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

The actual income tax rate differs from the statutory tax rate as shown in the following table:
		Years Ended December 31,
		2011		2010		2009
Statutory rate		35.00	%	35.00	%	35.00	%
Increase (decrease) in rate due to:
	Interest on tax-exempt securities and tax-free loans, net	(3.04	)	(3.36	)	(4.09	)
	Bank owned life insurance	(3.26	)	(3.94	)	(4.65	)
	State income tax (net)	0.72		0.68		0.15
	Tax credits	(2.12	)	(2.37	)	(1.97	)
	ESOP Dividends	(0.24	)	(0.29	)	(0.49	)
	Non-deductible meals and entertainment	0.29		0.30		0.28
	Other	0.48		0.47		(0.44	)
Effective tax rates		27.83	%	26.49	%	23.79	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Principal components of the Corporation's net deferred tax asset are summarized as follows:

		Years Ended
		December 31,
		2011			2010
Deferred tax assets:
	Allowance for credit losses	$	42,481		$	43,959
	Employee benefits	44,572			34,692
	REMIC	6,749			7,263
	Acquired liabilities	5,576			7,380
	Goodwill	13,041			14,314
	Core deposit intangible	1,066			649
	Other	1,875			35
		115,360			108,292
Deferred tax liabilities:
	Leased assets and depreciation	(4,776		)	(3,381		)
	Acquired loans	(35,533		)	(37,516		)
	Available for sale securities	(28,929		)	(18,697		)
	FHLB stock	(25,577		)	(25,577		)
	Loan fees and expenses	(4,618		)	(6,757		)
		(99,433		)	(91,928		)
Total net deferred tax asset		$	15,927		$	16,364

Change in Deferred Taxes [Table Text Block]

The period change in deferred taxes recorded both directly to capital and as a part of the income tax expense can be summarized as follows:
		Years ended
		December 31,
		2011			2010
Deferred tax changes reflected in other comprehensive income		$	1,193		$	(346	)
Deferred tax changes reflected in Federal income tax expense		(756		)	30,443
Deferred tax changes reflected in acquired net assets		—			(21,402		)
	Net change in deferred taxes	$	437		$	8,695

Summary of Income Tax Contingencies [Table Text Block]

A reconciliation of the change in the reserve for uncertain tax positions is as follows:

	Federal and State Tax			Accrued Interest and Penalties			Gross Unrecognized Income Tax Benefits
Balance at January 1, 2011	$	979		$	801		$	1,780
Additions for tax provisions related to prior year	18			1,414			1,432
Reduction for tax positions related to prior closed tax years	(44		)	(598		)	(642		)
Reduction for tax positions related to prior tax years	(7		)	(126		)	(133		)
Balance at December 31, 2011	$	946		$	1,491		$	2,437
Components of Reserve:
Potential adjustment to non-deductible interest expense	$	58		$	9		$	67
Timing of the accrual for interest on nonperforming assets	—			1,175			1,175
State income tax exposure	888			307			1,195
Balance at December 31, 2011	$	946		$	1,491		$	2,437