Deposits (Additional Information About Corporation's Deposits) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Deposits [Abstract]
Money market deposits obtained through brokers	$ 28,246	$ 24,700	$ 324,106
Deposits from the Certificate of Deposit Account Registry Service (CDARS) deposits	60,979	60,972	61,819
Deposits from foreign sources (primarily Mexico)	$ 729,933	$ 748,255	$ 776,448

The aggregate of all foreign interest-bearing and noninterest-bearing deposit liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Subparagraph a

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 235

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-05(a))

-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537907-122884

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_DepositsForeign
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant