Long-term Debt and Short-term Borrowings (Components of Short-term Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Total balance at December 31,	$ 177,025	$ 126,916	$ 148,132
Weighted average interest rate at December 31,	0.08%	0.08%	0.13%
Maximum month end balance during the year	$ 250,453	$ 247,170	$ 244,048
Average amount outstanding during the year	$ 205,305	$ 198,085	$ 208,267
Weighted average interest rate during the year	0.08%	0.11%	0.16%