Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 14,951	$ 59,475	$ 170,714
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	77,094	66,108	57,053
Non-cash interest expense, net	18,709	13,509	13,105
Non-cash change in fair value	710	3,884	0
Gain on asset acquisition and sale of business	(22,690)	0	0
Change in deferred revenue	(7,749)	6,966	(36,892)
Deferred income taxes	4,123	(45,426)	64,950
Share-based compensation	7,603	7,089	18,062
Impairment of long-term investment	3,312	200	0
Loss on extinguishment of debt	5,488	0	0
Loss (gain) on disposal of assets	119	8,323	0
Other	623	(625)	(2)
(Increase) decrease in assets:
Receivables	6,742	31,615	12,171
Deferred charges and other assets	(27,206)	(6,065)	19,426
Increase (decrease) in liabilities:
Accounts payable	(638)	6,203	(3,789)
Accrued compensation and other expenses	9,699	254	(3,218)
Accrued taxes payable and other tax contingencies	(1,457)	(4,718)	4,220
Net cash provided by operating activities	89,433	146,792	315,800
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of short-term investments	(92,436)	(142,555)	(930,016)
Sales of short-term investments	389,032	399,105	751,308
Purchases of property and equipment	(4,509)	(2,576)	(2,071)
Capitalized patent costs	(33,481)	(32,069)	(34,933)
Acquisition of patents	0	(2,250)	0
Acquisition of business, net of cash acquired	0	(142,985)	0
Proceeds from sale of business	10,000	0	0
Long-term investments	(350)	(6,686)	(4,585)
Net cash provided by (used in) investing activities	268,256	69,984	(220,297)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from exercise of stock options	2	6,723	382
Proceeds from issuance of senior convertible notes	400,000	0	0
Payments on long-term debt	(221,091)	0	0
Purchase of convertible bond hedge	(72,000)	0	0
Payment for warrant unwind	(4,184)	0	0
Prepayment penalty on long term debt	(10,763)	0	0
Proceeds from hedge unwind	9,038	0	0
Proceeds from issuance of warrants	47,600	0	0
Payments of debt issuance costs	(8,375)	0	0
Proceeds from non-controlling interests	15,666	0	6,801
Dividends paid	(44,580)	(48,468)	(43,255)
Shares withheld for taxes	(4,368)	(8,807)	(22,798)
Repurchase of common stock	(196,269)	(110,505)	(7,693)
Net cash used in financing activities	(89,324)	(161,057)	(66,563)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	268,365	55,719	28,940
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	488,733	433,014	404,074
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	$ 757,098	$ 488,733	$ 433,014