CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
OPERATING ACTIVITIES:
Net income	$ 2,551,360	$ 2,421,753	$ 1,892,798
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	101,517	78,241	48,365
Amortization	170,977	129,579	69,610
Provision for uncollectible accounts, net	24,324	22,990	16,451
Deferred income tax expense (benefit)	(61,335)	31,707	(11,104)
Stock-based compensation expense and other stock-based payments	249,133	189,292	142,098
Amortization of debt issuance costs	7,578	5,229	7,898
Amortization of debt discount	66,687	54,731	55,718
Loss on early extinguishment of debt	3	6,270	26,661
Changes in assets and liabilities:
Accounts receivable	(68,694)	(182,209)	(111,572)
Prepaid expenses and other current assets	(81,611)	(48,932)	(6,909)
Accounts payable, accrued expenses and other current liabilities	166,201	203,870	182,163
Other	(23,909)	1,876	(10,741)
Net cash provided by operating activities	3,102,231	2,914,397	2,301,436
INVESTING ACTIVITIES:
Purchase of investments	8,669,690	10,552,214	9,955,800
Proceeds from sale of investments	5,084,238	10,902,500	8,291,283
Additions to property and equipment	(173,915)	(131,504)	(84,445)
Acquisitions and other equity investments, net of cash acquired	(140,338)	(2,496,366)	(331,918)
Proceeds from foreign currency contracts	453,818	14,354	3,266
Payments on foreign currency contracts	(448,640)	(94,661)	(81,870)
Change in restricted cash	9	9,347	(2,783)
Net cash used in investing activities	(3,894,518)	(2,348,544)	(2,162,267)
FINANCING ACTIVITIES:
Proceeds from revolving credit facility	225,000	995,000	0
Payments related to revolving credit facility	(225,000)	(995,000)	0
Proceeds from the issuance of long-term debt	2,399,034	2,264,753	978,982
Payment of debt issuance costs - revolving credit facility	(4,005)	0	0
Payments related to conversion of senior notes	(147,629)	(125,136)	(414,569)
Repurchase of common stock	(3,089,055)	(750,378)	(883,515)
Payments of contingent consideration	(10,700)	0	0
Payments to purchase subsidiary shares from noncontrolling interests	0	0	(192,530)
Payments of stock issuance costs	0	0	(1,191)
Proceeds from exercise of stock options	20,851	16,389	91,607
Proceeds from the termination of conversion spread hedges	0	0	19
Excess tax benefits on stock-based awards	101,508	23,366	17,686
Net cash (used in) provided by financing activities	(729,996)	1,428,994	(403,511)
Effect of exchange rate changes on cash and cash equivalents	(149,103)	(136,190)	17,987
Net (decrease) increase in cash and cash equivalents	(1,671,386)	1,858,657	(246,355)
Cash and cash equivalents, beginning of period	3,148,651	1,289,994	1,536,349
Cash and cash equivalents, end of period	1,477,265	3,148,651	1,289,994
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the period for income taxes	534,105	491,530	391,169
Cash paid during the period for interest	54,299	16,950	20,954
Non-cash fair value increase for redeemable noncontrolling interests	0		42,522
Non-cash investing activity for contingent consideration	9,170	10,700	0
Non-cash financing activity for acquisitions	$ 0	$ 13,751	$ 1,546,748