Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities
Net income (loss)	$ (41,629)	$ 13,458
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Depreciation and amortization	7,092	7,109
Loss on disposal of fixed assets		46
Amortization of deferred financing costs	135	325
Amortization of premium on short-term investments	577	87
Deferred income taxes	32,534	(22,229)
Stock-based compensation	15,260	8,104
Tax benefit from stock-based compensation	(266)	(2,382)
Changes in operating assets and liabilities:
Accounts receivable	(4,237)	6,433
Prepaid expenses and other	734	(2,169)
Accounts payable	(1,087)	73
Accrued taxes	85	3,201
Accrued compensation and benefits	(5,094)	3,410
Accrued payables to customers		(30,640)
Other accrued liabilities	5,050	789
Net cash provided by (used in) operating activities	9,154	(14,385)
Cash flows from investing activities
Acquisition of property and equipment	(17,049)	(8,784)
Purchases of short-term investments, net	(31,100)	(47,854)
Sales of marketable securities	52,050	961
Maturities of marketable securities	21,415	1,000
Net cash provided by (used in) investing activities	25,316	(54,677)
Cash flows from financing activities
Net proceeds from issuance of common stock in initial public offering		111,105
Proceeds from revolving credit facility		23,424
Repayment of revolving credit facility		(23,424)
Repayment on long-term debt	(234)	(15,747)
Payment of deferred debt issuance costs		(200)
Proceeds from common stock issuances	10,279	7,198
Tax benefit from stock-based compensation	266	2,382
Net cash provided by financing activities	10,311	104,738
Net increase in cash and cash equivalents	44,781	35,676
Effect of exchange rate changes on cash and cash equivalents	(487)	(35)
Cash and cash equivalents at beginning of period	65,983	22,652
Cash and cash equivalents at end of period	$ 110,277	$ 58,293