Borrowings Securities Sold under Agreements to Repurchase (Details) (Securities Sold under Agreements to Repurchase [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Securities Sold under Agreements to Repurchase [Member]
Short-term Debt [Line Items]
Maximum outstanding at any month-end	$ 118,030	$ 132,380	$ 94,530
Average amount outstanding for the year	$ 113,443	$ 108,240	$ 76,758

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, maximum month-end borrowings during the period.

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

-Publisher SEC

-Name Industry Guide

-Number 3

-Section VII

-Subsection 2

Name:	us-gaap_ShorttermDebtMaximumMonthendOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration