Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities:
Net income	$ 435,336	$ 130,174
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	108,269	108,632
Stock-based compensation expense	62,276	40,807
Deferred taxes	2,294	(1,813)
Reduction in the carrying amount of operating lease right-of-use assets	37,261	43,256
Amortization and write-off of deferred financing fees	1,914	5,392
Amortization of deferred swap losses from de-designation	0	10,320
Gain on de-designated swaps	(11,751)	0
Changes in assets and liabilities:
Fees receivable, net	132,650	261,124
Deferred commissions	10,494	31,255
Prepaid expenses and other current assets	(822)	14,202
Other assets	(23,769)	(932)
Deferred revenues	190,814	(149,615)
Accounts payable and accrued and other liabilities	(212,321)	(93,885)
Cash provided by operating activities	732,645	398,917
Investing activities:
Additions to property, equipment and leasehold improvements	(24,479)	(45,865)
Acquisitions - cash paid (net of cash acquired)	(22,774)	0
Cash used in investing activities	(47,253)	(45,865)
Financing activities:
Proceeds from employee stock purchase plan	9,414	9,719
Proceeds from borrowings	600,000	800,000
Payments of deferred financing fees	(6,045)	(10,516)
Proceeds from revolving credit facility	0	327,000
Payments on revolving credit facility	(5,000)	(475,000)
Payments on borrowings	(105,256)	(853,094)
Purchases of treasury stock	(1,083,350)	(73,862)
Cash used in financing activities	(590,237)	(275,753)
Net increase in cash and cash equivalents and restricted cash	95,155	77,299
Effects of exchange rates on cash and cash equivalents	(7,281)	(1,502)
Cash and cash equivalents, beginning of period	712,583	280,836
Cash and cash equivalents and restricted cash, end of period	$ 800,457	$ 356,633