Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net income	$ 882,466	$ 807,799	$ 793,560
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	191,103	191,946	212,405
Stock-based compensation expense	129,841	90,566	98,570
Deferred taxes	(64,173)	(30,702)	(41,567)
Gain from sale of divested operation	(135,410)	0	0
Loss on impairment of lease related assets, net	20,368	53,970	49,537
Reduction in the carrying amount of operating lease right-of-use assets	70,207	70,086	75,125
Amortization and write-off of deferred financing fees	4,689	4,574	4,162
Gain on de-designated swaps	(3,925)	(52,308)	(20,204)
Changes in assets and liabilities, net of acquisitions and divestitures:
Fees receivable, net	(24,662)	(240,696)	(145,346)
Deferred commissions	(13,716)	5,574	(124,874)
Prepaid expenses and other current assets	(7,893)	(3,039)	(15,913)
Other assets	(34,528)	8,440	(18,287)
Deferred revenues	169,917	297,124	324,059
Accounts payable and accrued and other liabilities	(28,547)	(101,912)	121,243
Cash provided by operating activities	1,155,737	1,101,422	1,312,470
Investing activities:
Additions to property, equipment and leasehold improvements	(103,124)	(108,050)	(59,834)
Acquisitions - cash paid (net of cash acquired)	(3,800)	(9,508)	(22,939)
Proceeds from sale of divested operation	161,081	0	0
Other	0	0	2,306
Cash provided by (used in) investing activities	54,157	(117,558)	(80,467)
Financing activities:
Proceeds from employee stock purchase plan	25,107	22,231	18,173
Proceeds from borrowings	0	0	600,000
Payments for deferred financing fees	0	0	(7,320)
Payments on revolving credit facility	0	0	(5,000)
Payments on borrowings	(7,800)	(5,931)	(107,915)
Purchases of treasury stock	(606,188)	(1,043,742)	(1,655,547)
Cash used in financing activities	(588,881)	(1,027,442)	(1,157,609)
Net increase (decrease) in cash and cash equivalents and restricted cash	621,013	(43,578)	74,394
Effects of exchange rates on cash and cash equivalents and restricted cash	(13)	(18,425)	(26,375)
Cash and cash equivalents and restricted cash, beginning of year	698,599	760,602	712,583
Cash and cash equivalents and restricted cash, end of year	1,319,599	698,599	760,602
Cash paid during the year for:
Interest	119,038	112,825	101,885
Income taxes, net of refunds received	$ 306,682	$ 174,802	$ 253,379