Derivative Liabilities and Collateral Pledged (Details) (USD $)	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012
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Gross amounts of recognized liabilities	$ 199,999,000		$ 202,269,000	$ 234,188,000
Derivative Liabilities not subject to master netting agreements	18,600,000			12,300,000
Subject to Master Netting Agreements
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Gross amounts of recognized liabilities				221,840,000
Gross amounts offset in the Statement of Condition	0			0
Net amounts of liabilities presented in the Statement of Condition				221,840,000	[1],[2]
Derivative assets available for offset	(22,582,000)			(46,301,000)
Collateral pledged	(153,870,000)			(170,153,000)
Net amount	4,910,000			5,386,000
Interest Rate Contract [Member] | Subject to Master Netting Agreements
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Gross amounts of recognized liabilities	181,362,000			220,700,000
Net amounts of liabilities presented in the Statement of Condition	181,362,000	[1],[2]		220,700,000
Forwards And Futures [Member] | Subject to Master Netting Agreements
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Gross amounts of recognized liabilities				1,100,000
Net amounts of liabilities presented in the Statement of Condition				$ 1,100,000

[1] Included in Derivative Liabilities on the Consolidated Condensed Statements of Condition. As of March 31, 2013 and 2012, $18.6 million and $12.3 million, respectively, of derivative liabilities (primarily capital markets forward contracts) have been excluded from these tables because they are generally not subject to master netting or similar agreements.

[2] 2013 is comprised entirely of interest rate derivative contracts. 2012 includes $220.7 million of interest rate derivative contracts and $1.1 million of forwards and futures contracts.