Consolidated and Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 36,834	$ 28,621
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Deferred income taxes	(2,251)	277
Unrealized loss on financial instruments	21	771
(Gain) loss recognized on disposition of fixed assets	(50)	1,010
Realized gain on investments	(209)	0
Depreciation expense	14,830	13,568
Amortization of purchased intangible assets	7,041	6,920
Loss recognized on sale of available-for-sale marketable securities	0	28
Impairment of intangible asset	0	1,494
Stock-based compensation expense	16,094	14,990
Excess tax benefits from exercise and release of stock-based awards	(4,028)	(1,469)
Non-cash restructuring charges	0	146
Changes in operating assets and liabilities, excluding impact of acquisitions:
Accounts receivable	(18,724)	11,221
Unbilled revenues	(25,753)	(21,023)
Prepaid expenses and other current assets	(18,977)	(4,078)
Other assets	(521)	(179)
Accounts payable	1,508	5,162
Accrued compensation	(32,663)	(20,782)
Deferred revenues	(6,121)	(5,914)
Accrued expenses	15,511	1,133
Income taxes payable	(7,597)	4,353
Other long-term liabilities	8,075	4,134
Net cash (used in) provided by operating activities	(16,980)	40,383
Cash flows from investing activities:
Purchases of property and equipment and cost of internally developed software	(22,370)	(17,759)
Proceeds from sale of property and equipment	39	0
Cash paid for acquisitions of businesses, net of cash acquired	(12,812)	(4,993)
Cash paid for asset acquisitions	(1,500)	0
Sales of marketable securities classified as available-for-sale	0	1,372
Purchases of marketable securities classified as available-for-sale	0	(251)
Cash paid for acquisition of cost method investment	(5,526)	(200)
Cash received on financial instruments, net	172	77
Change in restricted cash balances	373	3,515
Net cash used in investing activities	(41,624)	(18,239)
Cash flows from financing activities:
Excess tax benefits from exercise and release of stock-based awards	4,028	1,469
Proceeds from issuance of common stock under stock plans	2,288	1,960
Payment of acquisition date fair value contingent consideration	(3,466)	0
Repurchases of common stock	(4,564)	0
Net cash (used in) provided by financing activities	(1,714)	3,429
Effect of exchange rate changes on cash and cash equivalents	3,825	(10,088)
Net (decrease) increase in cash and cash equivalents	(56,493)	15,485
Cash and cash equivalents at beginning of period	337,630	234,038
Cash and cash equivalents at end of period	281,137	249,523
Non-cash investing transactions:
Purchases of property and equipment for which cash had not been paid as of period end	3,379	2,659
Settlement of acquisition-related contingent consideration through releases from escrow	$ 0	$ 5,520