Notes Payable and Other Short-term Borrowings (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Securities sold under agreement to repurchase
Amounts outstanding at year-end	$ 51,702	$ 60,386
Year-end interest rate	0.63%	0.92%
Average daily balance during year	53,171	56,495
Maximum month-end balance during the year	$ 57,050	$ 61,240
Average interest rate during the year	0.70%	0.94%