SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)		1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Nov. 01, 2016 USD ($)	Feb. 29, 2016 USD ($)	Sep. 30, 2016 USD ($) $ / shares shares	Sep. 30, 2015 USD ($)	Mar. 31, 2012 USD ($)	Sep. 30, 2016 USD ($) Payment Plan $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Feb. 05, 2016 USD ($)
Cash, Cash Equivalents and Investments [Abstract]
Aggregate fair value of investments			$ 46,500,000			$ 46,500,000		$ 31,900,000
Fair Value Measurements [Abstract]
Unrealized gains (losses) on investments						0		0
Amortized premium included in interest income						(446,000)		(316,000)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			45,075,570			45,075,570		28,347,542
Held-to-maturity securities, noncurrent			1,443,099			1,443,099		3,596,541
Concentration Risk [Line Items]
Royalty revenue			6,119,815	$ 5,277,494		18,843,273	$ 15,574,234
Accounts receivable			3,846,752			3,846,752		2,547,920
Milestones Revenue [Abstract]
Recognized milestone revenue			0	1,000,000		0	1,000,000
Deferred Revenue [Abstract]
Deferred revenue recognized			12,345	12,345		37,034	$ 37,034
Deferred revenue			7,900,000			7,900,000		200,000
Nonrefundable upfront product license fees						62,000
Deferred revenue from foreign tax withholding			100,000			$ 100,000
Treasury Stock [Abstract]
Treasury stock purchased (in shares) | shares						24,020	27,433
Average price of share (in dollars per share) | $ / shares						$ 37.39	$ 43.07
Reimbursable Third Party Development Costs [Abstract]
Accrued patent costs			25,000			$ 25,000		20,000
Third Party Royalties [Abstract]
Royalty expenses			400,000	300,000		1,200,000	$ 1,000,000
Royalty Buy Down [Abstract]
Payment for royalty buy down					$ 1,500,000	$ 600,000
Number of additional cash payments for royalty buy down | Payment						5
Number of cash payments made for royalty obligation | Payment						3
Amount amortized related to agreement			247,000	221,000		$ 740,000	420,000
Deferred costs amortization period						5 years
Deferred royalty buy-down - long term			$ 3,100,000			$ 3,100,000
Share-based Compensation [Abstract]
Number of stock based compensation plans in effect | Plan						1
Additional Disclosures [Abstract]
Proceeds from stock option exercises						$ 529,300	2,813,984
Closing price of company stock (in dollars per share) | $ / shares			$ 45.67			$ 45.67
Comprehensive Income [Abstract]
Other comprehensive income			$ 0	0		$ 0	0
Provision for Income taxes [Abstract]
Unrecognized tax benefits			0	0		$ 0	0
Subsequent Event [Member]
Subsequent Event [Line Items]
Additional lease term extension period	1 year
Monthly base rent	$ 10,757
Notice period to cancel lease agreements	3 months
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment						5 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment						10 years
Recurring [Member] | Institutional Money Market [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents			1,894,904			$ 1,894,904		715,784
Recurring [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			6,917,696			6,917,696		6,617,042
Recurring [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			32,413,045			32,413,045		11,480,000
Recurring [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			7,187,928			7,187,928		13,847,041
Recurring [Member] | Level 1 [Member] | Institutional Money Market [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents			1,894,904			1,894,904		715,784
Recurring [Member] | Level 1 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Recurring [Member] | Level 1 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Recurring [Member] | Level 1 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			7,187,928			7,187,928		13,847,041
Recurring [Member] | Level 2 [Member] | Institutional Money Market [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents			0			0		0
Recurring [Member] | Level 2 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			6,917,696			6,917,696		6,617,042
Recurring [Member] | Level 2 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			32,413,045			32,413,045		11,480,000
Recurring [Member] | Level 2 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Recurring [Member] | Level 3 [Member] | Institutional Money Market [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents			0			0		0
Recurring [Member] | Level 3 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Recurring [Member] | Level 3 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Recurring [Member] | Level 3 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			0			0		0
Endo [Member]
Concentration Risk [Line Items]
Royalty revenue			6,900,000	6,300,000		19,600,000	16,600,000
Accounts receivable			3,800,000			3,800,000		2,500,000
Royalty / Mark-Up on Cost of Goods Sold [Abstract]
Deferred revenue on licensing agreements									$ 8,250,000
Proceeds from licensing agreement		$ 8,250,000	750,000	0		750,000	0
Deferred Revenue [Abstract]
Deferred revenue recognized			274,000	0		546,000	0
Deferred revenue			7,700,000			7,700,000
Municipal Bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			6,917,696			6,917,696		6,461,216
Held-to-maturity securities, noncurrent			0			0		155,826
Corporate Bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			31,218,996			31,218,996		9,882,285
Held-to-maturity securities, noncurrent			1,194,049			1,194,049		1,597,715
Certificates of Deposit [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			6,938,878			6,938,878		12,004,041
Held-to-maturity securities, noncurrent			249,050			249,050		$ 1,843,000
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense			$ 33,000	$ 33,000		$ 100,000	$ 72,000
Stock Options [Member]
Stock Option Activity [Roll Forward]
Outstanding, beginning of period (in shares) | shares						562,000
Grants (in shares) | shares						0	0
Exercised (in shares) | shares						(255,000)
Forfeitures or expirations (in shares) | shares						0
Outstanding, end of period (in shares) | shares			307,000			307,000		562,000
Exercisable, end of period (in shares) | shares			260,750			260,750
Weighted-Average Exercise Price [Roll Forward]
Outstanding, beginning of period (in dollars per share) | $ / shares						$ 11.91
Grants (in dollars per share) | $ / shares						0
Exercised (in dollars per share) | $ / shares						2.08
Forfeitures or expirations (in dollars per share) | $ / shares						0
Outstanding, end of period (in dollars per share) | $ / shares			$ 20.08			20.08		$ 11.91
Exercisable, end of period (in dollars per share) | $ / shares			$ 17.89			$ 17.89
Weighted Average Remaining Contractual Term [Roll Forward]
Weighted average remaining contractual term, outstanding						3 years 3 months 29 days		2 years 6 months 4 days
Weighted average remaining contractual term, exercisable						2 years 9 months 29 days
Aggregate Intrinsic Value [Roll Forward]
Aggregate intrinsic value, outstanding						$ 17,456,220
Aggregate intrinsic value, grants						0
Aggregate intrinsic value, exercised						0
Aggregate intrinsic value, forfeitures or expirations						0
Aggregate intrinsic value, outstanding			$ 7,857,070			7,857,070		$ 17,456,220
Aggregate intrinsic value, exercisable			7,243,095			7,243,095
Additional Disclosures [Abstract]
Proceeds from stock option exercises						500,000	$ 2,800,000
Unrecognized compensation cost related to non-vested stock options outstanding			$ 301,000			$ 301,000
Recognized compensation period						2 years 4 months 24 days