Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 8,983	$ 7,923
Other comprehensive income (loss):
Change in fair value of interest rate swap (cash flow hedge)	286	197
Unrealized holding (losses) gains arising during period (net of tax, $1,135 and $355 for three months ended March 31, 2013 and 2012)	(2,107)	662
Reclassification adjustment for losses included in net income (net of tax, $4 and $2 for three months ended March 31, 2013 and 2012)	7	3
Other comprehensive income (loss)	(1,814)	862
Comprehensive income	$ 7,169	$ 8,785