Short-term Borrowings (Balances and Rates) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Disclosure [Abstract]
Maximum month-end balance	$ 408,756,000	$ 298,662,000	$ 270,081,000
Average month-end balance	274,352,000	248,048,000	197,527,000
Weighted average interest rate for the year	0.31%	0.32%	0.44%
Weighted average interest rate at year-end	0.19%	0.31%	0.35%
Collateralized short-term borrowing under Discount Window Program	$ 100,800,000	$ 101,300,000