SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)		1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	Aug. 14, 2015 USD ($) ft²	Feb. 29, 2016 USD ($)	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2015 USD ($)	Mar. 31, 2012 USD ($)	Jun. 30, 2016 USD ($) Payment Plan $ / shares shares	Jun. 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			$ 38,900,000			$ 38,900,000		$ 31,900,000
Fair Value Measurements [Abstract]
Amortized premium included in interest income						(303,000)		(316,000)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			36,607,289			36,607,289		28,347,542
Held-to-maturity securities, noncurrent			2,264,531			2,264,531		3,596,541
Concentration Risk [Line Items]
Royalty revenue			6,167,811	$ 4,702,631		12,723,458	$ 10,296,740
Accounts receivable			4,279,440			4,279,440		2,547,920
Milestones Revenue [Abstract]
Recognized milestone revenue			0	0		0	0
Deferred Revenue [Abstract]
Deferred revenue recognized			12,345	12,344		24,689	$ 24,689
Deferred revenue			8,200,000			8,200,000		200,000
Nonrefundable upfront product license fees						74,068
Deferred revenue from foreign tax withholding			100,000			$ 100,000
Treasury Stock [Abstract]
Treasury stock purchased (in shares) | shares						18,730	17,943
Average price of share (in dollars per share) | $ / shares						$ 36.99	$ 39.07
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		800,000	$ 700,000
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			219,000	72,000		$ 493,000	199,000
Deferred costs amortization period						5 years
Deferred royalty buy-down - long term			$ 3,400,000			$ 3,400,000
Share-based Compensation [Abstract]
Number of stock based compensation plans in effect | Plan						1
Additional Disclosures [Abstract]
Proceeds from stock option exercises						$ 177,250	1,672,973
Closing price of company stock (in dollars per share) | $ / shares			$ 39.94			$ 39.94
Provision for Income taxes [Abstract]
Unrecognized tax benefits			$ 0	0		$ 0	0
Commitments and Contingencies [Abstract]
Additional lease term extension period	1 year
Area of sublease to landlord | ft²	1,000
Monthly base rent	$ 10,213
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			1,801,290			$ 1,801,290		715,784
Recurring [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			6,884,006			6,884,006		6,617,042
Recurring [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			24,101,824			24,101,824		11,480,000
Recurring [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments			7,885,990			7,885,990		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			1,801,290			1,801,290		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			7,885,990			7,885,990		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			6,884,006			6,884,006		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			24,101,824			24,101,824		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			6,200,000	4,700,000		12,700,000	10,300,000
Accounts receivable			4,300,000			4,300,000		2,500,000
Royalty / Mark-Up on Cost of Goods Sold [Abstract]
Deferred revenue on licensing agreements			8,250,000			8,250,000			$ 8,250,000
Proceeds from licensing agreement		$ 8,250,000
Deferred Revenue [Abstract]
Deferred revenue recognized			272,000	0		272,000	0
Municipal Bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			6,071,979			6,071,979		6,461,216
Held-to-maturity securities, noncurrent			812,773			812,773		155,826
Corporate Bonds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			22,649,320			22,649,320		9,882,285
Held-to-maturity securities, noncurrent			1,451,758			1,451,758		1,597,715
Certificates of Deposit [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, current			7,885,990			7,885,990		12,004,041
Held-to-maturity securities, noncurrent			0			0		$ 1,843,000
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense			$ 34,000	$ 33,000		$ 67,000	$ 39,000
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						(115,000)
Forfeitures or expirations (in shares) | shares						0
Outstanding, end of period (in shares) | shares			447,000			447,000		562,000
Exercisable, end of period (in shares) | shares			397,000			397,000
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						1.54
Forfeitures or expirations (in dollars per share) | $ / shares						0
Outstanding, end of period (in dollars per share) | $ / shares			$ 14.58			14.58		$ 11.91
Exercisable, end of period (in dollars per share) | $ / shares			$ 12.47			$ 12.47
Additional Disclosures [Abstract]
Weighted average remaining contractual term, Options outstanding						2 years 7 months 2 days		2 years 6 months 4 days
Weighted average remaining contractual term, Exercisable						2 years 1 month 10 days
Aggregate intrinsic value, Options outstanding						$ 17,456,220
Aggregate intrinsic value, Options grants						0
Aggregate intrinsic value, Options exercised						0
Aggregate intrinsic value, Options forfeitures or expirations						0
Aggregate intrinsic value, Options outstanding			$ 11,337,510			11,337,510		$ 17,456,220
Aggregate intrinsic value, Exercisable			10,905,935			10,905,935
Proceeds from stock option exercises						177,250	$ 1,700,000
Unrecognized compensation cost related to non-vested stock options outstanding			$ 334,000			$ 334,000
Recognized compensation period						2 years 8 months 8 days