Consolidated Statements of Cash Flows - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income		$ 536	$ 425
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		256	226
Non-cash interest expense, net of amortization of premium		10	7
Provision for doubtful accounts		38	27
Amortization of deferred income related to equity method investment		(1)	(1)
Loss on extinguishment of debt		0	1
Loss on unconsolidated entity investments, net		3	10
Dividend received from unconsolidated entity investment		1	1
Loss on restructuring		24	0
Loss (gain) on other investments		1	(3)
Share-based payment expense		107	127
Deferred income taxes		116	146
Amortization of right-of-use assets		28	2
Changes in operating assets and liabilities:
Receivables		134	(69)
Inventory		(4)	6
Related party, net		9	(1)
Prepaid expenses and other current assets		(13)	(20)
Other long-term assets		10	7
Accounts payable and accrued expenses		(136)	36
Accrued interest		(3)	6
Deferred revenue		(105)	(4)
Operating lease liabilities		(26)	7
Other long-term liabilities		22	5
Net cash provided by operating activities		1,007	941
Cash flows from investing activities:
Additions to property and equipment		(149)	(160)
Purchases of other investments		(7)	(7)
Acquisition of business, net of cash acquired		(28)	313
Sale of short-term investments		0	72
Investments in related parties and other equity investees		(84)	(9)
Repayment from related party		3	0
Net cash (used in) provided by investing activities		(265)	209
Cash flows from financing activities:
Proceeds from exercise of stock options		0	1
Taxes paid from net share settlements for stock-based compensation		(43)	(47)
Revolving credit facility, net of deferred financing costs		0	(439)
Proceeds from long-term borrowings, net of costs		1,483	1,236
Proceeds from sale of capped call security		0	3
Principal payments of long-term borrowings		(5)	(156)
Common stock repurchased and retired		(399)	(1,474)
Dividends paid		(117)	(113)
Net cash provided by (used in) financing activities		919	(989)
Net increase in cash, cash equivalents and restricted cash		1,661	161
Cash, cash equivalents and restricted cash at beginning of period		120	65
Cash, cash equivalents and restricted cash at end of period	[1]	1,781	226
Cash paid during the period for:
Interest, net of amounts capitalized		194	171
Income taxes paid		10	5
Non-cash investing and financing activities:
Treasury stock not yet settled		(9)	(28)
Fair value of shares issued related to acquisition of a business		0	2,355
Accumulated other comprehensive (loss) income, net of tax		$ (15)	$ 14

[1] The following table reconciles cash, cash equivalents and restricted cash per the statement of cash flows to the balance sheet. The restricted cash balances are primarily due to letters of credit which have been issued to the landlords of leased office space. The terms of the letters of credit primarily extend beyond one year. Cash and cash equivalents : June 30, 2020: $1,770, December 31, 2019: $106, June 30, 2019: $215, December 31, 2018: $54
Restricted cash included in Other long-term assets: June 30, 2020: $11, December 31, 2019: $14, June 30, 2019: $11, December 31, 2018: $11 Total cash, cash equivalents and restricted cash at end of period: June 30, 2020: $1,781, December 31, 2019: $120, June 30, 2019: $226, December 31, 2018: $65