Consolidated Statement of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Cash flows—operating activities:
Net income	$ 452.1	$ 426.4	$ 358.1
Less: income from discontinued operations	4.5	248.3	48.5
Income from continuing operations	447.6	178.1	309.6
Depreciation and amortization	128.0	96.0	91.1
Net gains on investments	(153.8)	(2.4)	(163.6)
Gain recognized on step-up of unconsolidated affiliates	(43.8)	0.0	0.0
Gains on sale of properties and businesses	(0.6)	(5.6)	(4.5)
Amortization of share-based compensation	43.6	12.2	24.1
Equity in earnings of unconsolidated affiliates	(54.5)	(27.2)	(45.4)
Cash dividends from unconsolidated affiliates	0.0	0.4	3.5
Deferred income taxes	(27.1)	17.0	(15.5)
Changes in accounts receivable	13.9	(16.0)	(10.6)
Changes in other assets	(127.9)	(0.8)	(9.4)
Changes in client funds obligations	(17.1)	10.9	9.9
Changes in client funding receivable	17.1	(10.9)	(9.9)
Changes in accounts payable and accrued liabilities	(39.9)	16.6	(1.8)
Changes in income taxes payable	12.1	(67.9)	(31.6)
Changes in deferred revenues and gains	(29.6)	(4.6)	(2.1)
Changes in accrued compensation and benefits	(10.2)	(26.9)	(7.7)
Other, net	6.2	(6.2)	(0.4)
Net cash provided from continuing operating activities	164.0	162.7	135.7
Net cash provided from (used in) discontinued operating activities	(12.1)	26.4	84.5
Net cash provided from operating activities	151.9	189.1	220.2
Cash flows—investing activities:
Cash paid for capital expenditures	(78.8)	(60.4)	(88.9)
Investments in securities	(62.8)	(258.3)	(166.4)
Proceeds from (investments in and advances to) unconsolidated affiliates, net	32.7	(23.8)	11.1
Proceeds from sale / maturities of investments	102.6	317.8	358.6
Net increase (decrease) in restricted cash and cash equivalents held to satisfy client funds obligations	43.3	(20.3)	(113.5)
Proceeds from sale of properties	0.0	5.7	6.1
Acquisition of businesses, net of cash and cash equivalents acquired	(38.9)	(93.5)	(117.4)
Proceeds from sale of businesses, net of cash and cash equivalents sold	1.2	14.5	7.9
Other, net	0.0	1.0	0.1
Net cash used in continuing investing activities	(0.7)	(117.3)	(102.4)
Net cash provided from discontinued investing activities	40.6	412.9	104.9
Net cash provided from investing activities	39.9	295.6	2.5
Cash flows—financing activities:
Proceeds from issuance of common stock	2.8	5.3	11.8
Principal payments on debt	(108.2)	(5.1)	(46.4)
Proceeds from issuance of senior notes	350.0	0.0	0.0
Net proceeds (repayments) on accounts receivable securitization program	(88.3)	103.2	(120.0)
Net borrowings (repayments) on revolving credit facilities	(75.0)	(151.1)	181.8
Net increase (decrease) in client funds obligations	(43.3)	20.3	124.0
Receipt of third party capital in investment fund	0.8	7.1	15.0
Common stock repurchased	(310.6)	(315.8)	(405.3)
Payment of cash dividends	(43.7)	(43.4)	(43.1)
Excess tax benefits from share-based compensation	0.0	4.7	5.6
Other, net	(1.9)	0.0	(2.1)
Net cash used for continuing financing activities	(317.4)	(374.8)	(278.7)
Net cash used for discontinued financing activities	(0.2)	0.0	(6.1)
Net cash used for financing activities	(317.6)	(374.8)	(284.8)
Effect of exchange rates on cash and cash equivalents	6.8	0.0	0.0
Net increase (decrease) in cash and cash equivalents, including cash within assets held for sale	(119.0)	109.9	(62.1)
Cash and cash equivalents, beginning of year	199.5	89.6	151.7
Cash and cash equivalents, end of year	80.5	199.5	89.6
Less: cash and cash equivalents held for sale	0.0	4.0	10.1
Cash and cash equivalents of continuing operations, end of year	$ 80.5	$ 195.5	$ 79.5