Derivative financial instruments (Details 1) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset designated as hedging instrument, fair value	$ 107,089	$ 101,517
Derivative asset not designated as hedging instrument, fair value	406,125	370,048
Derivative liability not designated as hedging instrument, fair value	372,234	335,767
Derivative liability designated as hedging instrument, fair value	1,270	1,062
Total derivative asset, fair value	513,214	471,565
Total derivative liability, fair value	373,504	336,829
Interest rate swap agreements [Member]
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset designated as hedging instrument, fair value	106,177	96,637
Derivative liability designated as hedging instrument, fair value	0	0
Interest rate contracts [Member]
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset not designated as hedging instrument, fair value	364,064	345,632
Derivative liability not designated as hedging instrument, fair value	339,440	321,461
Foreign exchange and other option and futures contracts [Member]
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset not designated as hedging instrument, fair value	26,920	11,267
Derivative liability not designated as hedging instrument, fair value	27,043	11,761
Commitments to sell real estate loans [Member]
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset designated as hedging instrument, fair value	912	4,880
Derivative asset not designated as hedging instrument, fair value	1,583	10,322
Derivative liability not designated as hedging instrument, fair value	5,364	1,962
Derivative liability designated as hedging instrument, fair value	1,270	1,062
Mortgage-related commitments to originate real estate loans for sale [Member]
Information about fair values of derivative instruments in consolidated balance sheet
Derivative asset not designated as hedging instrument, fair value	13,558	2,827
Derivative liability not designated as hedging instrument, fair value	$ 387	$ 583

Fair value of a derivative asset (or nonderivative instrument) that is designated and qualifies as a hedging instrument, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 205G

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44C
-Subparagraph a
-Clause 1

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- Definition

Fair value of a derivative asset that is not designated or qualifying as a hedging instrument, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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- Definition

Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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- Definition

Fair value of a derivative liability (or nonderivative instrument) that is designated and qualifies as a hedging instrument, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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Fair value of a derivative liability that is not designated or qualifying as a hedging instrument, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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