Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 85,520	$ 66,053	$ 58,807
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	38,700	31,392	35,126
Amortization and impairment of other intangible assets	10,306	11,726	15,521
Acquisition-related contingent consideration	2,164	(1,200)	(1,676)
Provision for doubtful accounts	8,912	15,564	18,252
Non-cash share-based compensation	16,920	17,951	22,848
Non-cash interest expense	1,985	2,521	2,691
Loss on early extinguishment of debt		19,589
Other	(1,204)	(760)	(522)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, billed and unbilled	3,471	(35,648)	(43,072)
Notes receivable	3,145	3,106	(18,253)
Prepaid expenses and other assets	(2,840)	(3,557)	10,733
Accounts payable, accrued expenses and other	3,268	(4,718)	980
Income taxes	22,012	18,491	15,283
Accrued compensation	40,350	4,780	11,106
Billings in excess of services provided	779	(5,370)	7,577
Net cash provided by operating activities	233,488	139,920	135,401
Investing activities
Payments for acquisition of businesses, net of cash received	(1,251)	(575)	(23,467)
Purchases of property and equipment	(28,935)	(31,399)	(39,256)
Other	54	237	5,128
Net cash used in investing activities	(30,132)	(31,737)	(57,595)
Financing activities
Borrowings (repayments) under revolving line of credit, net	(130,000)	200,000
Payments of long-term debt		(425,671)	(6,014)
Payments of debt issue costs		(3,843)
Deposits	4,006	3,227	13,071
Purchase and retirement of common stock	(21,489)	(26,532)	(4,367)
Net issuance of common stock under equity compensation plans	21,708	16,666	4,772
Other	465	191	(1,132)
Net cash (used in) provided by financing activities	(125,310)	(235,962)	6,330
Effect of exchange rate changes on cash and cash equivalents	(11,648)	(6,141)	(6,289)
Net increase (decrease) in cash and cash equivalents	66,398	(133,920)	77,847
Cash and cash equivalents, beginning of period	149,760	283,680	205,833
Cash and cash equivalents, end of period	216,158	149,760	283,680
Supplemental cash flow disclosures
Cash paid for interest	23,154	46,965	48,169
Cash paid for income taxes, net of refunds	20,270	20,654	27,326
Non-cash investing and financing activities:
Issuance of stock units under incentive compensation plans	$ 1,842	$ 2,124	$ 1,674