Mortgage Servicing Rights (Schedule of Information Relates to Serviced Loan Portfolio) (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Mortgage Servicing Rights
Balance of loans serviced for others	$ 1,751,700,000		$ 1,751,700,000		$ 1,603,414,000
MSR as a percentage of serviced loans			0.93%		0.90%
Contractually specified servicing fees, late fees and ancillary fees earned	$ 1,100,000	$ 933,000	$ 2,300,000	$ 1,800,000

The total amount of contractually specified servicing fees, late fees, and ancillary fees earned for each period for which results of operations are presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6863725&loc=d3e122596-111746

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 140
-Paragraph 17
-Subparagraph c
-Clause 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_ContractuallySpecifiedServicingFeesLateFeesAndAncillaryFeesEarnedInExchangeForServicingFinancialAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration