Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating activities
Net income	$ 270,871	$ 280,088	$ 274,892
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	45,764	43,910	41,079
Amortization of intangible assets	3,479	4,183	6,159
Amortization of notes receivable	73,602	51,621	27,784
Provision for expected credit losses	42,836	50,315	35,149
Share-based compensation	39,324	38,436	29,534
Deferred income taxes	23,745	(16,605)	(25,453)
Other	1,182	303	5,743
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, billed and unbilled	(34,260)	18,340	(229,296)
Notes receivable, net of repayments	(255,006)	(99,892)	(50,703)
Prepaid expenses and other assets	(15,611)	(2,810)	7,606
Accounts payable, accrued expenses and other	6,627	12,875	8,687
Income taxes	(67,963)	(29,441)	29,335
Accrued compensation	29,631	43,503	50,186
Billings in excess of services provided	(12,089)	271	13,759
Net cash provided by operating activities	152,132	395,097	224,461
Investing activities
Purchases of property and equipment and other	(58,531)	(35,408)	(49,479)
Purchase and maturity of short-term investment	0	25,246	(24,356)
Net cash used in investing activities	(58,531)	(10,162)	(73,835)
Financing activities
Borrowings under revolving line of credit	1,280,000	600,000	835,000
Repayments under revolving line of credit	(915,000)	(600,000)	(835,000)
Repayment of convertible notes	0	0	(315,763)
Purchase and retirement of common stock	(858,681)	(10,217)	(20,982)
Share-based compensation tax withholdings	(18,545)	(19,021)	(16,375)
Proceeds on stock option exercises	1,392	10,887	1,297
Deposits and other	358	2,968	(2,840)
Net cash used in financing activities	(510,476)	(15,383)	(354,663)
Effect of exchange rate changes on cash and cash equivalents	21,473	(12,281)	15,571
Net increase (decrease) in cash and cash equivalents	(395,402)	357,271	(188,466)
Cash and cash equivalents, beginning of period	660,493	303,222	491,688
Cash and cash equivalents, end of period	265,091	660,493	303,222
Supplemental cash flow disclosures
Cash paid for interest	19,666	5,918	14,390
Cash paid for income taxes and tax credits, net of refunds	144,357	116,729	79,588
Non-cash investing and financing activities:
Issuance of stock units under incentive compensation plans	2,069	2,805	2,274
Excise tax on purchase and retirement of common stock	7,953	0	0
Non-cash additions to property and equipment	$ 4,459	$ 2,623	$ 950