Income per Share Applicable to Common Stockholders (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Basic net income per common share:
Net income	$ 1,125	$ 192
Basic income per common share (in dollars per share)	$ 0.03	$ 0.01
Weighted-average common shares outstanding	37,547	33,826
Diluted net income per common share:
Net income	$ 1,125	$ 192
Diluted income per common share (in dollars per share)	$ 0.03	$ 0.00
Weighted-average common shares used to compute diluted net income per share	40,459	39,431