UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES:
Net income	$ 1,175,832	$ 955,062
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	85,123	65,157
Amortization	84,179	85,426
Provision for uncollectible accounts, net	26,127	16,117
Deferred income tax benefit	(40,939)	(79,863)
Stock-based compensation expense and other stock-based payments	126,047	121,016
Amortization of debt issuance costs	4,509	3,744
Amortization of debt discount	35,386	34,180
Loss on early extinguishment of debt	1,027	0
Impairment of cost-method investments	0	63,208
Excess tax benefits on stock-based awards and other equity deductions	0	61,470
Changes in assets and liabilities:
Accounts receivable	(333,545)	(344,147)
Prepaid expenses and other current assets	(438,641)	(286,976)
Accounts payable, accrued expenses and other current liabilities	873,705	683,395
Other	3,024	(10,563)
Net cash provided by operating activities	1,601,834	1,367,226
INVESTING ACTIVITIES:
Purchase of investments	(2,869,903)	(2,701,662)
Proceeds from sale of investments	1,480,236	2,176,868
Additions to property and equipment	(147,269)	(113,699)
Acquisitions and other investments, net of cash acquired	(490)	(795)
Net cash used in investing activities	(1,537,426)	(639,288)
FINANCING ACTIVITIES:
Proceeds from short-term borrowing	4,599	0
Proceeds from the issuance of long-term debt	1,051,722	994,705
Payments related to conversion of senior notes	(83,473)	0
Payments for repurchase of common stock	(555,250)	(520,566)
Proceeds from exercise of stock options	2,790	9,766
Net cash provided by financing activities	420,388	483,905
Effect of exchange rate changes on cash, cash equivalents and restricted cash	68,570	4,627
Net increase in cash, cash equivalents and restricted cash	553,366	1,216,470
Cash, cash equivalents and restricted cash, beginning of period	2,082,007	1,478,071
Cash, cash equivalents and restricted cash, end of period	2,635,373	2,694,541
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the period for income taxes	577,247	496,403
Cash paid during the period for interest	60,308	43,727
Non-cash financing activity	$ 1,000	$ 0