Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Income Statement [Abstract]
Revenue	$ 449,157	$ 371,065		$ 312,828
Cost of revenue	266,198	223,538		181,209
Gross margin	182,959	147,527		131,619
Expenses:
Selling, general and administrative	87,146	78,197		66,415
Depreciation and amortization	9,738	7,273		4,410
Research and development	4,976	3,752		3,182
Loss (gain) on disposal of long-lived assets	211	(421)		(1,009)
Total expenses	102,071	88,801		72,998
Income from operations	80,888	58,726		58,621
Other income (expense):
Loss on extinguishment of debt	0	0		(7,257)
Change in fair value of warrant liability	0	0		2,649
Interest expense	(1,610)	(2,092)		(8,103)
Other income (expense), net	(394)	316		(452)
Total other income (expense)	(2,004)	(1,776)		(13,163)
Income before income taxes	78,884	56,950		45,458
Income tax (expense) benefit	(25,281)	(20,772)		4,333
Net income	$ 53,603	$ 36,178		$ 49,791
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 0.98	$ 0.70	[1]	$ 1.03
Diluted earnings per common share (in dollars per share)	$ 0.97	$ 0.67	[1]	$ 0.97
Weighted average common shares:
Weighted average common shares used in computing basic earnings per common share (in shares)	54,511	51,346		48,185
Weighted average common shares used in computing diluted earnings per common share (in shares)	55,526	53,841		53,554

[1] The sum of the quarterly earnings per share (basic and diluted) may not agree to the earnings per share for the year due to the timing of common stock issuances.