CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 58,840,000	$ 103,885,000	$ 48,070,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred revenue and recognition of unbilled receivables	(68,905,000)	(11,122,000)	(7,406,000)
Depreciation	8,612,000	4,919,000	4,270,000
Amortization of intangibles	21,962,000	21,983,000	16,492,000
Inventory write-down	3,630,000	0	0
Amortization of premium and discount on investments, net	(6,131,000)	(2,871,000)	(1,830,000)
Stock-based compensation to employees	12,432,000	12,284,000	11,374,000
Stock-based compensation to Board of Directors and Scientific Advisory Board	4,364,000	2,609,000	1,715,000
Change in earnout liability recorded for Adesis acquisition		519,000
Deferred income tax (benefit) expense	(12,814,000)	24,396,000	3,094,000
Excess tax benefits from share-based payment arrangements			(4,232,000)
Retirement plan benefit expense	4,466,000	4,351,000	3,965,000
Decrease (increase) in assets:
Accounts receivable	9,226,000	(27,361,000)	1,205,000
Inventory	(37,365,000)	(18,951,000)	(4,460,000)
Other current assets	4,860,000	(3,884,000)	(3,870,000)
Deferred income taxes	20,682,000
Other assets	(63,922,000)	(297,000)	(133,000)
Increase (decrease) in liabilities:
Accounts payable and accrued expenses	1,563,000	16,420,000	4,362,000
Other current liabilities	5,761,000	(1,917,000)	4,362,000
Deferred revenue	130,639,000	8,402,000	3,360,000
Other liabilities	23,896,000
Net cash provided by operating activities	121,796,000	133,365,000	80,338,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(25,391,000)	(29,803,000)	(7,300,000)
Purchase of intangibles			(95,989,000)
Purchase of business, net of cash acquired			(33,380,000)
Purchases of investments	(628,789,000)	(594,283,000)	(450,277,000)
Proceeds from sale of investments	633,179,000	498,508,000	548,474,000
Net cash used in investing activities	(21,001,000)	(125,578,000)	(38,472,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	798,000	734,000	439,000
Repurchase of common stock	(477,000)
Proceeds from the exercise of common stock options		38,000	185,000
Payment of withholding taxes related to stock-based compensation to employees	(11,620,000)	(9,432,000)	(4,870,000)
Excess tax benefits from share-based payment arrangements			4,232,000
Cash dividends paid	(11,314,000)	(5,652,000)
Net cash used in financing activities	(22,613,000)	(14,312,000)	(14,000)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	78,182,000	(6,525,000)	41,852,000
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	132,840,000	139,365,000	97,513,000
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 211,022,000	$ 132,840,000	$ 139,365,000