Fair Value Measurements (Narrative) (Detail) $ / shares in Units, shares in Millions			1 Months Ended	3 Months Ended			6 Months Ended
	Aug. 02, 2018 USD ($)	Jul. 08, 2016 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($) numberOfNotesRecivables	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2020 USD ($) numberOfNotesRecivables	Jun. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)	Aug. 03, 2018 USD ($)	Jul. 09, 2016 USD ($)	Dec. 31, 2015 $ / shares	Dec. 15, 2015 shares	Sep. 18, 2015 USD ($)	Nov. 06, 2014 USD ($)	Jun. 26, 2014 USD ($)	Oct. 18, 2013 USD ($)
Intangible assets, net			$ 13,186,000	$ 12,550,000			$ 12,550,000
Investment Owned, at Cost			6,600,000	6,600,000			6,600,000
Financing Receivable, before Allowance for Credit Loss, Noncurrent				$ 52,100,000			$ 52,100,000
Cash payment for purchase of royalty right															$ 65,600,000
Purchase of royalty rights	$ 20,000,000.0
Reversionary interest period										$ 481,000,000.0
Sensitivity range for royalty disclosures				2.50%			2.50%
Sensitivity - decrease in fair value from increase in discount rate				$ 400,000			$ 400,000
Number of notes receivable assets | numberOfNotesRecivables				2			2
Transfers from level 1 to level 2, amount			0	$ 0			$ 0
Transfers from level 2 to level 1, amount			0	0			0
Percentage of royalty acquired															75.00%
Revenues				5,211,000	$ 7,458,000		11,206,000	$ 14,154,000
Finite-Lived Intangible Assets, Gross			16,115,000	16,115,000			16,115,000
Asset Impairment Charges			10,800,000			$ 8,200,000
Convertible Notes Payable, Carrying Value			27,250,000	13,507,000			13,507,000
Notes Payable, Fair Value Disclosure			33,900,000	$ 16,200,000			16,200,000
Depomed [Member]
Cash payment for purchase of royalty right																	$ 240,500,000
Purchase of royalty rights																	241,300,000
Royalty right purchase transaction costs																	$ 800,000
Cash flow model expected royalty sales term				9 years
Sensitivity - decrease in fair value from increase in discount rate				$ 16,600,000			16,600,000
Sensitivity - increase in fair value from decrease in discount rate				19,400,000			19,400,000
Sensitivity to increase or decrease in expected royalty				5,300,000			5,300,000
Royalty rights				207,700,000			207,700,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				207,700,000			$ 207,700,000
Contractual cap on potential royalty asset multiple							2
VB [Member]
Purchase of royalty rights																$ 15,500,000
Royalty rights				4,300,000			$ 4,300,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				$ 4,300,000			$ 4,300,000
Contractual cap on potential royalty asset multiple							2.3
University of Michigan [Member]
Cash flow model expected royalty sales term				2 years
Sensitivity - increase in fair value from decrease in discount rate				$ 400,000			$ 400,000
Sensitivity to increase or decrease in expected royalty				$ 400,000			$ 400,000
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate				12.80%			12.80%
Royalty rights				$ 17,100,000			$ 17,100,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				17,100,000			$ 17,100,000
AcelRx [Member]
Purchase of royalty rights														$ 65,000,000.0
Period to give notice to terminate license agreement							180 days
Royalty rights				0			$ 0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				0			$ 0
Percentage of royalty acquired														75.00%
Percentage of first four milestone payments acquired														80.00%
Number of potential milestone royalties														4
Contractual cap on potential royalty asset multiple							3
Kybella [Member]
Purchase of royalty rights											$ 9,500,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				$ 200,000			$ 200,000
Maximum amount of additional funds, upon attainment of milestones		$ 1,000,000.0
Alphaeon [Member]
Investment Owned, Balance, Shares | shares													1.7
Investment estimated fair value, per share | $ / shares												$ 3.84
Minimum [Member] | Depomed [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate				10.00%			10.00%
Maximum [Member] | Depomed [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate				24.00%			24.00%
Income generating assets [Member]
Revenues				$ 63,000	36,000		$ 73,000	6,000
Pharmaceutical [Member]
Revenues				0	0		0	0
Discontinued Operations, Held-for-sale [Member]
Loss on classification as held for sale				(16,143,000)	0		(28,904,000)	0
Intangible assets, net			10,112,000	9,723,000			9,723,000
Loss on classification as held for sale			0	(28,402,000)			(28,402,000)
Royalty rights			266,196,000	234,242,000			234,242,000
Revenues				(8,137,000)	$ (29,984,000)		16,288,000	$ 2,233,000
Discontinued Operations, Held-for-sale [Member] | Depomed [Member]
Loss on classification as held for sale				4,500,000
Discontinued Operations, Held-for-sale [Member] | VB [Member]
Loss on classification as held for sale				100,000
Discontinued Operations, Held-for-sale [Member] | University of Michigan [Member]
Loss on classification as held for sale				400,000
Discontinued Operations, Held-for-sale [Member] | AcelRx [Member]
Loss on classification as held for sale				0
Discontinued Operations, Held-for-sale [Member] | Kybella [Member]
Loss on classification as held for sale				100,000
Discontinued Operations, Held-for-sale [Member] | Income generating assets [Member]
Loss on classification as held for sale				5,000,000.0
Discontinued Operations, Held-for-sale [Member] | Pharmaceutical [Member]
Estimated cost to sell									$ 1,800,000
Loss on classification as held for sale, fair value adjustment									4,900,000
Loss on classification as held for sale				$ 16,800,000			$ 16,800,000		$ 6,700,000
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate				17.00%			17.00%		19.00%
Fair Value Level 3 [Member]
Royalty rights			$ 266,196,000	$ 234,242,000			$ 234,242,000
Notes Receivable, Fair Value Disclosure				$ 57,300,000			$ 57,300,000