CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES:
Net income	$ 2,421,753	$ 1,892,798	$ 1,424,037
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	78,241	48,365	32,818
Amortization	129,579	69,610	32,323
Provision for uncollectible accounts, net	22,990	16,451	16,094
Deferred income tax expense (benefit)	31,707	(11,104)	19,596
Stock-based compensation expense and other stock based payments	189,292	142,098	72,035
Amortization of debt issuance costs	5,229	7,898	5,212
Amortization of debt discount	54,731	55,718	39,820
Loss on early extinguishment of debt	6,270	26,661	0
Changes in assets and liabilities:
Accounts receivable	(182,209)	(111,572)	(105,277)
Prepaid expenses and other current assets	(48,932)	(6,909)	(40,793)
Accounts payable, accrued expenses and other current liabilities	203,870	182,163	256,021
Other	1,876	(10,741)	33,864
Net cash provided by operating activities	2,914,397	2,301,436	1,785,750
INVESTING ACTIVITIES:
Purchase of investments	(10,552,214)	(9,955,800)	(6,352,495)
Proceeds from sale of investments	10,902,500	8,291,283	4,799,412
Additions to property and equipment	(131,504)	(84,445)	(55,158)
Acquisitions and other equity investments, net of cash acquired	(2,496,366)	(331,918)	(33,861)
Proceeds from foreign currency contracts	14,354	3,266	86,159
Payments on foreign currency contracts	(94,661)	(81,870)	(4,014)
Change in restricted cash	9,347	(2,783)	(2,756)
Net cash used in investing activities	(2,348,544)	(2,162,267)	(1,562,713)
FINANCING ACTIVITIES:
Proceeds from revolving credit facility	995,000	0	0
Payments related to revolving credit facility	(995,000)	0	0
Proceeds from the issuance of long-term debt	2,282,217	980,000	1,000,000
Payment of debt issuance costs	(17,464)	(1,018)	(20,916)
Payments related to conversion of senior notes	(125,136)	(414,569)	(1)
Repurchase of common stock	(750,378)	(883,515)	(257,021)
Payments to purchase subsidiary shares from noncontrolling interests	0	(192,530)	(61,079)
Payments of stock issuance costs	0	(1,191)	0
Proceeds from exercise of stock options	16,389	91,607	2,683
Proceeds from the termination of conversion spread hedges	0	19	0
Excess tax benefit from stock-based compensation	23,366	17,686	5,189
Net cash provided by (used in) financing activities	1,428,994	(403,511)	668,855
Effect of exchange rate changes on cash and cash equivalents	(136,190)	17,987	11,621
Net increase (decrease) in cash and cash equivalents	1,858,657	(246,355)	903,513
Cash and cash equivalents, beginning of period	1,289,994	1,536,349	632,836
Cash and cash equivalents, end of period	3,148,651	1,289,994	1,536,349
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the period for income taxes	491,530	391,169	300,539
Cash paid during the period for interest	16,950	20,954	13,933
Non-cash fair value increase for redeemable noncontrolling interests	0	42,522	84,693
Non-cash investing activity for contingent consideration	10,700	0	0
Non-cash financing activity for acquisitions	$ 13,751	$ 1,546,748	$ 0