Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net income	$ 5,687	$ 9,320	$ 25,712	$ 29,584
Basic-weighted average shares outstanding	27,518,000	28,438,000	27,744,000	28,265,000
Effect of dilutive potential securities	316,000	283,000	367,000	356,000
Diluted- weighted average shares outstanding	27,834,000	28,721,000	28,111,000	28,621,000
Basic (per share)	$ 0.21	$ 0.33	$ 0.93	$ 1.05
Diluted (per share)	$ 0.20	$ 0.32	$ 0.91	$ 1.03
Shares excluded from computation of earnings per share	0	400,000	0	400,000