UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
OPERATING ACTIVITIES:
Net income	$ 331,218	$ 244,292
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,552	9,802
Amortization	22,824	9,278
Provision for uncollectible accounts, net	3,671	4,216
Deferred income taxes	8,828	(7,229)
Stock-based compensation expense and other stock-based payments	39,412	21,826
Amortization of debt issuance costs	1,346	1,432
Amortization of debt discount	12,412	11,120
Loss on early extinguishment of debt	3,396	0
Changes in assets and liabilities:
Accounts receivable	(94,156)	(115,162)
Prepaid expenses and other current assets	(317,812)	(207,993)
Accounts payable, accrued expenses and other current liabilities	147,608	188,112
Other	2,705	23,423
Net cash provided by operating activities	177,004	183,117
INVESTING ACTIVITIES:
Purchase of investments	(2,612,047)	(1,504,676)
Proceeds from sale of investments	2,652,013	1,521,947
Additions to property and equipment	(29,731)	(15,051)
Acquisitions and other equity investments, net of cash acquired	(2,633)	(102)
Payments on foreign currency contracts	(43,380)	(17,539)
Change in restricted cash	(5,077)	(581)
Net cash used in investing activities	(40,855)	(16,002)
FINANCING ACTIVITIES:
Payments related to conversion of senior notes	(58,449)	0
Repurchase of common stock	(96,660)	(76,380)
Proceeds from exercise of stock options	7,693	965
Excess tax benefit on stock-based compensation	5,499	4,443
Net cash used in financing activities	(141,917)	(70,972)
Effect of exchange rate changes on cash and cash equivalents	3,924	(21,282)
Net (decrease) increase in cash and cash equivalents	(1,844)	74,861
Cash and cash equivalents, beginning of period	1,289,994	1,536,349
Cash and cash equivalents, end of period	1,288,150	1,611,210
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the period for income taxes	367,160	228,893
Cash paid during the period for interest	5,821	9,072
Non-cash fair value increase for redeemable noncontrolling interests	$ 0	$ 42,768