Notes Receivable and Other Long-term Receivables (Narrative) (Detail) $ / shares in Units, $ in Thousands, shares in Millions								1 Months Ended	3 Months Ended			9 Months Ended			12 Months Ended			58 Months Ended
		Jan. 08, 2018 USD ($)	Sep. 21, 2017 USD ($)	Sep. 22, 2015 USD ($)	Jun. 26, 2015 USD ($) $ / shares shares	Aug. 15, 2013 USD ($)	Feb. 28, 2013	Jan. 31, 2013 USD ($)	Sep. 30, 2019 USD ($)		Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)		Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)		Dec. 31, 2013 USD ($)	Apr. 30, 2018	Feb. 02, 2018 $ / shares	Oct. 07, 2015 $ / shares	Sep. 30, 2014 USD ($)	Apr. 01, 2014 USD ($)	Jun. 28, 2013 USD ($)	Mar. 05, 2013 USD ($)	Nov. 02, 2012 USD ($)	Jan. 27, 2012 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Revenues									$ 44,165		$ 67,898	$ 60,552		$ 152,991
Repayment of notes receivable												5,000		0
Accounts Receivable, Net, Noncurrent	[1]														$ 1,400
Investment Owned, at Cost									6,600			6,600			6,600
Commitments and Contingencies										[1]			[1]			[2]
Financial Instruments, Owned, Other, at Fair Value									10,923			10,923			62
Asset Impairment Charges									0			0			$ 8,200
Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Gross																					$ 53,900
Gain Contingency, Unrecorded Amount									55,800			55,800
Financing Receivable, Net									50,200			50,200
Interest rate of note receivable (in Percent)						5.00%
Avinger [Member]
Accounts Notes And Loans Receivable [Line Items]
Repayment of notes receivable				$ 21,400
Hyperion [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Gross																										$ 2,300
Number of payments to be received																										2
Periodic contractual payments																								$ 1,200
kaleo Note Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Gross																						$ 150,000
Repayment of notes receivable			$ 141,700
CareView [Member]
Accounts Notes And Loans Receivable [Line Items]
Interest rate of note receivable (in Percent)					13.50%
Amount company has agreed to advance under agreement					$ 40,000
Tranche 1 of note receivable					20,000
Tranche 2 of note receivable					$ 20,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares					4.4
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares					$ 0.45														$ 0.03	$ 0.40
Financial Instruments, Owned, Other, at Fair Value									100			100
Credit Agreement [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Gross																									$ 40,000
Credit agreement, stated interest rate (in Percent)																									5.00%
Proceeds received under remedies available for borrower's breach of terms credit agreement								$ 8,100
Forbearance number of days under terms of credit agreement (in Duration)							120 days
Amount company has agreed to advance under agreement																	$ 8,700
Financing Receivable, Modifications, Post-Modification Recorded Investment						$ 44,100
Initial Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment						33,700
Additional Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Gross																							$ 1,300
Royalty Agreement [Member] | Avinger [Member]
Accounts Notes And Loans Receivable [Line Items]
Reduction in royalty rate (in percent)																		50.00%
Term loan and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment						1,300
Forbearance principal and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment						$ 9,100
License and other [Member]
Accounts Notes And Loans Receivable [Line Items]
Revenues		$ 500							$ (45)		$ 40	$ (48)		$ 614

[1] unaudited

[2] Note 1