Borrowed Funds (Summary of Short Term Borrowings) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Borrowed Funds [Abstract]
Outstanding at end of period	$ 38,633	$ 39,257
Weighted average interest rate at end of period	0.14%	0.34%
Maximum amount outstanding as of any month end	38,633	52,367
Average amount outstanding	$ 38,465	$ 38,812
Approximate weighted average rate during the period	0.14%	0.34%