Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net income	$ 74,816	$ 52,522
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,067	6,082
Amortization of operating lease right-of-use assets	1,645	1,291
Stock-based compensation expense	6,677	5,196
Deferred taxes	2,734	2,022
Other	2,036	(587)
Changes in operating assets and liabilities:
(Increase) in accounts receivable	(31,640)	(13,453)
Decrease in prepaid expenses and other assets	8,539	5,264
Decrease in trading investments	56,394	6,015
(Decrease) in accrued employee compensation	(25,436)	(22,354)
Increase in income and other tax liabilities	1,950	2,267
Increase in deferred revenue	451	735
Increase (decrease) in accounts payable, accrued expenses and other liabilities	15,941	(3,764)
(Decrease) in operating lease liabilities	(1,516)	(321)
Net cash provided by operating activities	120,369	39,369
Cash flows from investing activities
Acquisition of business, net of cash and cash equivalents acquired	(533)
Proceeds from maturities and sales, available-for-sale investments	45,154	67,603
Purchases, available-for-sale investments	(8,995)	(53,193)
Purchases of furniture, equipment and leasehold improvements	(4,291)	(649)
Capitalization of software development costs	(6,778)	(3,184)
Other		(15)
Net cash provided by investing activities	24,557	10,562
Cash flows from financing activities
Cash dividend on common stock	(23,244)	(19,412)
Exercise of stock options	80	172
Withholding tax payments on restricted stock vesting and stock option exercises	(21,243)	(11,803)
Repurchases of common stock	(5,415)	(5,184)
Net cash (used in) financing activities	(49,822)	(36,227)
Effect of exchange rate changes on cash and cash equivalents	(3,360)	943
Cash and cash equivalents including restricted cash
Net increase for the period	91,744	14,647
Beginning of period	274,253	247,458
End of period	365,997	262,105
Non-cash activity
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	674
Mutual Funds Held In Rabbi Trust [Member]
Changes in operating assets and liabilities:
Decrease in trading investments	$ (289)	$ (1,546)

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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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