CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net income	$ 323,187	$ 218,798
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	65,600	44,689
Depreciation and amortization	10,376	10,382
Stock-based compensation	1,463	1,251
Amortization of debt discount and issuance costs	6,778	6,230
Amortization of discount on short-term investments	0	(343)
Amortization of lease guarantee	0	135
Changes in fair values of equity and long-term investments, net	(132,485)	(39,245)
Other non-cash items	(251)	14
Changes in operating assets and liabilities:
Receivables from collaborative arrangements	(7,340)	(12,723)
Prepaid expenses and other current assets	1,098	264
Accounts payable	23	613
Accrued personnel-related expenses and other accrued liabilities	(533)	252
Accrued interest payable	(2,484)	(2,484)
Net cash provided by operating activities	265,432	227,833
Cash flows from investing activities
Maturities of marketable securities	0	86,000
Purchases of marketable securities	0	(12,943)
Purchases of equity and long term investments	(46,373)	(72,500)
Distributions of equity and long-term investments	110,000	0
Purchases of property and equipment	0	(13)
Net cash provided by investing activities	63,627	544
Cash flows from financing activities
Repurchase of common stock	(394,149)	0
Distributions to noncontrolling interest	(46,358)	(27,962)
Repurchase of shares to satisfy tax withholding	(47)	(83)
Proceeds from issuances of common stock, net	123	421
Net proceeds from the issuance of variable interest entity's equity	0	344
Net cash used in financing activities	(440,431)	(27,280)
Net increase (decrease) in cash and cash equivalents	(111,372)	201,097
Cash and cash equivalents at beginning of period	246,487	278,096
Cash and cash equivalents at end of period	135,115	479,193
Supplemental disclosure of cash flow information
Cash paid for interest	$ 9,933	$ 9,933