Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 2,020	$ 2,554	$ 1,457
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	586	535	610
Stock-based compensation	130	135	124
Deferred taxes	27	(654)	120
Cetip realized investment gain, net	0	(114)	0
Trayport gain, net	0	(110)	0
Gain on acquisition of remaining MERS interest	(110)	0	0
Other	(24)	(22)	(6)
Changes in assets and liabilities:
Customer accounts receivable	(44)	(135)	(65)
Other current and non-current assets	(45)	(24)	7
Section 31 fees payable	(33)	(2)	14
Deferred revenue	1	8	28
Other current and non-current liabilities	25	(86)	(140)
Total adjustments	513	(469)	692
Net cash provided by operating activities	2,533	2,085	2,149
Investing activities
Capital expenditures	(134)	(220)	(250)
Capitalized software development costs	(146)	(137)	(115)
Proceeds from sale of Cetip, net	0	438	0
Cash paid for acquisitions, net of cash acquired	(1,246)	(423)	(425)
Cash received from divestitures	0	761	0
Purchases of investments	(306)	(327)	(70)
Proceeds from investments	77	0	0
Net cash provided by (used in) investing activities	(1,755)	92	(860)
Financing activities
Proceeds from debt facilities, net	2,213	984	0
Repayments of debt facilities	(600)	(850)	0
Repayments of commercial paper, net	(283)	(409)	(949)
Repurchases of common stock	(1,198)	(949)	(50)
Dividends to stockholders	(555)	(476)	(409)
Payments relating to treasury shares	(80)	(88)	(54)
Acquisition of non-controlling interest and redeemable non-controlling interest	(35)	(174)	0
Proceeds from issuance of redeemable non-controlling interest	71	0	0
Other	4	(9)	0
Net cash used in financing activities	(463)	(1,971)	(1,462)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash and cash equivalents	(11)	12	(24)
Net increase (decrease) in cash, cash equivalents, and restricted cash and cash equivalents	304	218	(197)
Cash, cash equivalents, and restricted cash and cash equivalents at beginning of year	1,568	1,350	1,547
Cash, cash equivalents, and restricted cash and cash equivalents at end of year	1,872	1,568	1,350
Supplemental cash flow disclosure
Cash paid for income taxes	533	594	460
Cash paid for interest	202	171	170
Supplemental non-cash investing and financing activity
Treasury stock retirement	$ 0	$ 0	$ 1,512