Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net income (loss)	$ 56,728	$ 45,395
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	16,049	15,111
Amortization and impairment of other intangible assets	5,196	6,019
Acquisition-related contingent consideration	1,340	(1,304)
Provision for doubtful accounts	4,344	6,571
Non-cash share-based compensation	9,667	10,581
Non-cash interest expense	992	1,343
Other	(639)	(223)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, billed and unbilled	(57,501)	(70,710)
Notes receivable	(4,640)	(6,626)
Prepaid expenses and other assets	(943)	(5,120)
Accounts payable, accrued expenses and other	1,932	(2,435)
Income taxes	29,329	16,458
Accrued compensation	(28,518)	(40,587)
Billings in excess of services provided	7,297	(5,204)
Net cash provided by (used in) operating activities	40,633	(30,731)
Investing activities
Payments for acquisition of businesses, net of cash received	(56)	(576)
Purchases of property and equipment	(11,983)	(17,533)
Other	96	64
Net cash used in investing activities	(11,943)	(18,045)
Financing activities
Payments of debt issue costs		(3,090)
Deposits	2,557	2,423
Purchase and retirement of common stock	(2,903)
Net issuance of common stock under equity compensation plans	9,353	8,662
Other	(154)	(326)
Net cash provided by financing activities	8,853	7,669
Effect of exchange rate changes on cash and cash equivalents	(4,638)	(2,585)
Net increase (decrease) in cash and cash equivalents	32,905	(43,692)
Cash and cash equivalents, beginning of period	149,760	283,680
Cash and cash equivalents, end of period	182,665	239,988
Supplemental cash flow disclosures
Cash paid for interest	11,242	23,047
Cash paid for income taxes, net of refunds	4,493	9,121
Non-cash investing and financing activities:
Issuance of stock units under incentive compensation plans	$ 1,842	$ 2,124