Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 4,569	$ 4,540
Property and equipment, accumulated depreciation	15,629	14,478
Intangible assets, accumulated amortization	$ 461	$ 405
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	49,673,909	49,118,373
Common stock, shares outstanding	49,673,909	49,118,373