Notes Receivable and Other Long-term Receivables (Narrative) (Detail) $ / shares in Units, $ in Thousands, shares in Millions				1 Months Ended	3 Months Ended			12 Months Ended
	Jun. 26, 2015 USD ($) $ / shares shares	Aug. 15, 2013 USD ($)	Feb. 28, 2013	Jan. 31, 2013 USD ($)	Mar. 31, 2020 USD ($)		Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2019 USD ($)		Feb. 02, 2018 $ / shares	Oct. 07, 2015 $ / shares	Sep. 30, 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					$ 5,995		$ 6,696
Investment Owned, at Cost					6,600					$ 6,600
Commitments and Contingencies						[1]					[2]
Financial Instruments, Owned, Other, at Fair Value					11,698					$ 14,152
Asset Impairment Charges					0			$ 8,200
Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss														$ 53,900
Gain Contingency, Unrecorded Amount					55,800
Financing Receivable, after Allowance for Credit Loss					50,200
Interest rate of note receivable (in Percent)		5.00%
Hyperion [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss																		$ 2,300
Number of payments to be received																		2
Periodic contractual payments																$ 1,200
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
Credit Agreement [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss																	$ 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, Troubled Debt Restructuring, Postmodification		$ 44,100
Initial Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		33,700
Additional Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss															$ 1,300
Term loan and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		1,300
Forbearance principal and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 9,100
License and other [Member]
Accounts Notes And Loans Receivable [Line Items]
Revenues					$ 10		$ (33)

[1] unaudited

[2] Note 1