Derivative Assets And Collateral Received (Details) (USD $)	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012
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Gross amounts of recognized assets	$ 274,332,000		$ 292,472,000	$ 340,337,000
Derivative Assets not subject to master netting agreements	15,800,000			7,200,000
Subject to Master Netting Agreements
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Gross amounts of recognized assets				333,146,000
Gross amounts offset in the Statement of Condition	0			0
Net amounts of assets presented in the Statement of Condition				333,146,000	[1],[2]
Derivative liabilities available for offset	(22,582,000)			(46,301,000)
Collateral Received	(234,562,000)			(265,428,000)
Net amount	1,390,000			21,417,000
Interest Rate Contract [Member] | Subject to Master Netting Agreements
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Gross amounts of recognized assets	258,534,000			307,900,000
Net amounts of assets presented in the Statement of Condition	258,534,000	[1],[2]		307,900,000
Forwards And Futures [Member] | Subject to Master Netting Agreements
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Gross amounts of recognized assets				25,200,000
Net amounts of assets presented in the Statement of Condition				$ 25,200,000

[1] Included in Derivative Assets on the Consolidated Condensed Statements of Condition. As of March 31, 2013 and 2012, $15.8 million and $7.2 million, respectively, of derivative assets (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 $307.9 million of interest rate derivative contracts and $25.2 million of forwards and futures contracts.