Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 175,635	$ 183,766	$ 182,801
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles	47,131	39,412	34,442
Stock-based compensation expense	46,149	38,845	34,735
Excess tax benefits from employee stock-based compensation exercises	(13,860)	(20,193)	(25,392)
Deferred taxes	344	(759)	16,663
Amortization and write-off of debt issue costs	1,512	2,645	2,710
Changes in assets and liabilities:
Fees receivable, net	(44,476)	(76,424)	(28,097)
Deferred commissions	(13,236)	(12,340)	(18,608)
Prepaid expenses and other current assets	(13,268)	(3,017)	(1,187)
Other assets	(14,733)	(7,139)	(5,268)
Deferred revenues	91,840	105,354	80,938
Accounts payable, accrued, and other liabilities	82,523	96,629	41,917
Cash provided by operating activities	345,561	346,779	315,654
Investing activities:
Additions to property, equipment and leasehold improvements	(46,128)	(38,486)	(36,498)
Acquisitions (net of cash acquired)	(170,604)	(109,928)	0
Acquisitions - increase in restricted cash (escrow)	(25,625)	(14,363)	0
Cash used in investing activities	(242,357)	(162,777)	(36,498)
Financing activities:
Proceeds from employee stock-based compensation plans and ESP Plan	7,499	7,767	6,042
Proceeds from borrowings	440,000	400,000	205,625
Payments on debt	(20,000)	(200,000)	(205,625)
Purchases of treasury stock	(509,049)	(432,006)	(181,736)
Fees paid for debt refinancing	0	(4,624)	(3,553)
Excess tax benefits from employee stock-based compensation exercises	13,860	20,193	25,392
Cash used by financing activities	(67,690)	(208,670)	(153,855)
Net increase (decrease) in cash and cash equivalents	35,514	(24,668)	125,301
Effects of exchange rates on cash and cash equivalents	(27,840)	(34,020)	(1,163)
Cash and cash equivalents, beginning of period	365,302	423,990	299,852
Cash and cash equivalents, end of period	372,976	365,302	423,990
Cash paid during the period for:
Interest	21,200	10,600	8,500
Income taxes, net of refunds received	$ 83,500	$ 70,100	$ 50,767