Long-term Debt and Short-term Borrowings (Components of Short-term Borrowings) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Disclosure [Abstract]
Total Balance at December 31,	$ 148,132	$ 201,243	$ 313,757
Weighted average interest rate at December 31,	0.13%	0.16%	0.24%
Maximum month end balance during the year	244,048	398,853	452,903
Average amount outstanding during the year	$ 208,267	$ 320,338	$ 389,582
Weighted average interest rate during the year	0.16%	0.19%	0.27%