Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities
Net income	$ 6,937	$ 16,121	$ 1,142
Adjustments to reconcile net income including non-controlling interests to net cash provided by operating activities:
Depreciation and amortization of property and equipment	12,301	7,511	6,658
Amortization of other intangible assets	1,655	2,491	3,848
Stock-based compensation	3,450	867	740
Interest on note receivable from stockholder			(3)
Forgiveness on note receivable from stockholder	103
Change in fair value of preferred stock warrants	132	68	46
Change in deferred taxes	2,828	(10,401)	270
Changes in operating assets and liabilities, net of effect of acquisition:
Accounts receivable	564	(2,006)	1,346
Unbilled receivables	(223)	(1,224)	(1,140)
Prepaid expenses and other assets	750	190	710
Accounts payable	(1,236)	1,686	49
Accrued expenses and other liabilities	(83)	(382)	(1,532)
Deferred revenue	2,351	9,239	2,388
Net cash provided by operating activities	29,529	24,160	14,522
Cash flows from investing activities
Decrease (increase) in restricted cash	536	966	(317)
Purchases of short-term marketable securities		(9,373)
Proceeds from sale of short-term marketable securities	9,373		1,644
Purchases of property and equipment	(16,917)	(11,256)	(4,321)
Purchase of acquired assets			(350)
Payments for patents, trademarks and domain	(156)		(99)
Payments for business acquisition, net of cash acquired			(62)
Contractual payments related to business acquisition	(171)	(271)	(154)
Net cash used in investing activities	(7,335)	(19,934)	(3,659)
Cash flows from financing activities
Proceeds from issuance of common stock upon initial public offering	48,297
Offering costs	(2,586)
Proceeds from exercise of stock options	1,028	2	39
Excess tax benefits from stock-based compensation	246
Payments of capital leases	(420)	(738)	(596)
Payments to non-controlling interests	(547)	(398)	(417)
Net cash provided by (used in) financing activities	46,018	(1,134)	(974)
Net increase in cash and cash equivalents	68,212	3,092	9,889
Cash and cash equivalents at beginning of year	25,721	22,629	12,740
Cash and cash equivalents at end of year	93,933	25,721	22,629
Supplemental disclosure of cash flow information
Cash paid for interest	11	30	57
Cash paid for taxes	1,357	1,030	134
Supplemental disclosure of non-cash investing and financing activities
Conversion of convertible preferred stock into common stock	124,602
Retirement of treasury stock	4,575
Property and equipment and software maintenance costs in accounts payable, accrued expenses and other liabilities	1,995	3,319	1,171
Accretion of convertible preferred stock	1,633	5,020	5,259
Exercise and conversion of preferred stock warrants into common stock	272
Acquisition of software, equipment and software maintenance services under capital leases	402	73	815
Offering costs related to stock options issued to non-employee consultant	27
Contractual payments related to business acquisition in accrued expenses and other liabilities	14	47	77
Offering costs in accounts payable, accrued expenses and other liabilities	$ 10