CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Issued [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Non-controlling interest [Member]
Beginning Balance, Shares at Dec. 31, 2015		266,545	(77,237)
Beginning Balance at Dec. 31, 2015	$ 1,419,073	$ 2,665	$ (189,753)	$ 1,789,449	$ (190,235)	$ (4,242)	$ 11,189
Stock-based compensation				34,544
Common stock issued under stock compensation plans, net of shares withheld for employee taxes, Shares		1,452
Common stock issued under stock compensation plans, net of shares withheld for employee taxes		$ 15		(8,133)
Issuance of treasury stock, Shares			0
Issuance of treasury stock	0		$ 0	0
Tax deficiency realized upon exercise of stock-based awards				(1,280)
Accretion of redemption preference on redeemable convertible non-controlling interest - discontinued operations				(28,536)
Purchase of treasury stock, Shares			(10,250)
Purchase of treasury stock			$ (121,240)
Warrants issued				3,915
Net (loss) income less net income attributable to non-controlling interests					2,884
Foreign currency translation adjustments, net	(1,528)					(1,528)
Unrecognized gain on derivatives qualifying as cash flow hedges, net of tax						361
Unrecognized gain (loss) on available for sale securities, net of tax						(56,420)
Acquisition of non-controlling interest				0			29,400
ASC 606 implementation adjustments | ASC 606					0
Net (loss) income attributable to non-controlling interests	146						146
Recognition of previously unrecognized excess tax benefits					0
Ending Balance, Shares at Dec. 31, 2016		267,997	(87,487)
Ending Balance at Dec. 31, 2016	1,273,201	$ 2,680	$ (310,993)	1,789,959	(187,351)	(61,829)	40,735
Stock-based compensation				35,337
Common stock issued under stock compensation plans, net of shares withheld for employee taxes, Shares		1,338
Common stock issued under stock compensation plans, net of shares withheld for employee taxes		$ 13		(5,767)
Issuance of treasury stock, Shares			22
Issuance of treasury stock	334		$ 335	(76)
Tax deficiency realized upon exercise of stock-based awards				0
Accretion of redemption preference on redeemable convertible non-controlling interest - discontinued operations				(43,850)
Subsidiary issuance of common stock				1,473
Purchase of treasury stock, Shares			(1,039)
Purchase of treasury stock			$ (12,077)
Warrants issued				3,983
Net (loss) income less net income attributable to non-controlling interests					(152,609)
Foreign currency translation adjustments, net	3,352					3,352
Unrecognized gain on derivatives qualifying as cash flow hedges, net of tax						72
Unrecognized gain (loss) on available for sale securities, net of tax						56,420
Acquisition of non-controlling interest				0			21
ASC 606 implementation adjustments | ASC 606					0
Net (loss) income attributable to non-controlling interests	$ (1,566)						(1,566)
Recognition of previously unrecognized excess tax benefits					1,810
Ending Balance, Shares at Dec. 31, 2017	269,335	269,335	(88,504)
Ending Balance at Dec. 31, 2017	$ 1,160,072	$ 2,693	$ (322,735)	1,781,059	(338,150)	(1,985)	39,190
Stock-based compensation				34,638
Common stock issued under stock compensation plans, net of shares withheld for employee taxes, Shares		1,620
Common stock issued under stock compensation plans, net of shares withheld for employee taxes		$ 16		(8,197)
Issuance of treasury stock, Shares			76
Issuance of treasury stock	1,121		$ 1,121	(61)
Tax deficiency realized upon exercise of stock-based awards				0
Accretion of redemption preference on redeemable convertible non-controlling interest - discontinued operations				72,386
Subsidiary issuance of common stock				0
Purchase of treasury stock, Shares			(11,303)
Purchase of treasury stock			$ (138,929)
Warrants issued				2,729
Net (loss) income less net income attributable to non-controlling interests					412,334
Foreign currency translation adjustments, net	(2,908)					(2,908)
Unrecognized gain on derivatives qualifying as cash flow hedges, net of tax						(496)
Unrecognized gain (loss) on available for sale securities, net of tax						0
Acquisition of non-controlling interest				(1,060)			(5,349)
ASC 606 implementation adjustments | ASC 606					58,658
Net (loss) income attributable to non-controlling interests	$ (4,527)						(4,527)
Recognition of previously unrecognized excess tax benefits					0
Ending Balance, Shares at Dec. 31, 2018	270,955	270,955	(99,731)
Ending Balance at Dec. 31, 2018	$ 1,580,427	$ 2,709	$ (460,543)	$ 1,881,494	$ 132,842	$ (5,389)	$ 29,314