Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Summary of earnings per share
Net income	$ 12,758	$ 8,874	$ 25,010	$ 21,057
Weighted Average Shares (in shares)
BASIC SHARES	22,888,155	21,623,827	22,856,132	21,592,416
EFFECT OF DILUTIVE SECURITIES	52,144	20,377	49,104	22,251
DILUTIVE SHARES	22,940,299	21,644,204	22,905,236	21,614,667
NET INCOME PER SHARE (in dollars per share)
BASIC EPS	$ 0.56	$ 0.41	$ 1.09	$ 0.98
EFFECT OF DILUTIVE SECURITIES				$ (0.01)
DILUTIVE EPS	$ 0.56	$ 0.41	$ 1.09	$ 0.97