Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 3,440	$ 3,651
Weighted average shares outstanding: [Abstract]
Basic (in shares)	46,385	47,519
Effect of dilutive securities: [Abstract]
Stock options and employee stock purchase plan (in shares)	1,195	1,079
Diluted (in shares)	47,580	48,598
Basic (in dollars per share)	$ 0.07	$ 0.08
Diluted (in dollars per share)	$ 0.07	$ 0.08
Anti-dilutive stock options excluded from diluted earnings per share computations (in shares)	3	1,199