Securities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost	$ 554,202	$ 447,496
Gross Unrealized Gains	7,459	7,070
Gross Unrealized Losses	(737)	(441)
Total	560,924	454,125
U.S. Treasuries
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost		9,865
Gross Unrealized Gains		555
Total		10,420
U.S. government sponsored enterprises
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost	25,717	65,784
Gross Unrealized Gains	379	1,101
Gross Unrealized Losses	(4)
Total	26,092	66,885
Mortgage-backed: residential
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost	360,345	298,324
Gross Unrealized Gains	4,886	3,988
Gross Unrealized Losses	(125)	(106)
Total	365,106	302,206
States and political subdivisions
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost	129,168	49,733
Gross Unrealized Gains	1,554	1,284
Gross Unrealized Losses	(604)	(58)
Total	130,118	50,959
Corporate
Amortized cost, unrealized gains and losses and fair value of securities available for sale were
Amortized Cost	38,972	23,790
Gross Unrealized Gains	640	142
Gross Unrealized Losses	(4)	(277)
Total	$ 39,608	$ 23,655

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

WEST SUBURBAN BANCORP INC 10-Q