CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 85,565	$ 60,754
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	14,940	10,200
Operating lease right-of-use assets amortization expense	16,816	12,187
Bad debt expense	2,719	(133)
Deferred taxes	8,288	846
Stock-based compensation expense	11,881	21,856
Other	5,893	520
Changes in assets and liabilities:
Trade receivables and contract assets	(51,423)	(48,343)
Prepaid and other assets	(9,746)	401
Accounts payable	(2,407)	(2,488)
Accrued expenses and other liabilities	5,437	(22,360)
Operating lease liabilities	(15,646)	(13,175)
Income taxes payable	(9,062)	(20,467)
Net cash provided by/(used in) operating activities	63,255	(202)
Cash flows from investing activities:
Purchases of property and equipment	(29,075)	(13,424)
Acquisition of business, net of cash acquired (Note 2)	(10,339)	0
Payments for cost method investments	(20,000)	(5,000)
Other investing activities, net	(71)	(136)
Net cash used in investing activities	(59,485)	(18,560)
Cash flows from financing activities:
Proceeds from stock option exercises	6,850	11,402
Payments of withholding taxes related to net share settlements of restricted stock units	(1,018)	(1,208)
Payment of contingent consideration for previously acquired business	(7,869)	0
Other financing activities, net	(9)	(13)
Net cash (used in)/provided by financing activities	(2,046)	10,181
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(22,009)	548
Net decrease in cash, cash equivalents and restricted cash	(20,285)	(8,033)
Cash, cash equivalents and restricted cash, beginning of period	937,688	771,711
Cash, cash equivalents and restricted cash, end of period	$ 917,403	$ 763,678