Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities:
Net income	$ 39,306	$ 30,762
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,977	2,943
Equity-based compensation	4,670	4,040
(Gain) loss on disposal of equipment	(15)	1
Tax benefit of stock awards exercised/vested	6,954	4,987
Excess tax benefits from equity-based compensation	(6,916)	(4,874)
Deferred income taxes	879	2,265
Unrealized foreign currency gain	(174)	(372)
Changes in operating assets and liabilities:
Accounts receivable, net	(15,320)	(6,971)
Other assets	(4,305)	227
Accounts payable, accrued and other liabilities	(4,148)	(7,341)
Income taxes	(8,786)	887
Deferred revenue	5,910	7,142
Net cash provided by operating activities	21,032	33,696
Investing activities:
Purchase of property and equipment	(3,580)	(1,633)
Net purchases of investments	(1,441)	(2,055)
Net cash used in investing activities	(5,021)	(3,688)
Financing activities:
Purchase of common stock	(58,305)	(34,902)
Proceeds from issuance of common stock from options exercised	829	3,861
Excess tax benefits from equity-based compensation	6,916	4,874
Net cash used in financing activities	(50,560)	(26,167)
Foreign currency impact on cash	1,295	(1,955)
Net change in cash and cash equivalents	(33,254)	1,886
Cash and cash equivalents at beginning of period	124,375	96,737
Cash and cash equivalents at end of period	$ 91,121	$ 98,623