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
		Sep. 21, 2017 USD ($)	Feb. 14, 2017 USD ($)	Feb. 09, 2017 USD ($)	Feb. 06, 2017 USD ($)	Dec. 30, 2016 USD ($)	Aug. 26, 2016 USD ($)	Jul. 16, 2016 $ / shares	Oct. 27, 2015 USD ($)	Sep. 22, 2015 USD ($)	Jun. 26, 2015 USD ($) $ / shares shares	Nov. 10, 2014 USD ($)	Nov. 05, 2013 USD ($)	Oct. 03, 2013 USD ($)	Aug. 15, 2013 USD ($)	Jan. 31, 2013 USD ($)	Sep. 30, 2017 USD ($)		Sep. 30, 2017 USD ($)		Sep. 30, 2016 USD ($)	Dec. 31, 2013 USD ($)	Apr. 30, 2018	Dec. 31, 2016 USD ($)		Nov. 14, 2016 USD ($)	Sep. 29, 2016 $ / shares	Sep. 12, 2016 USD ($) $ / shares	Aug. 25, 2016 USD ($)	Jul. 15, 2016 USD ($)	Dec. 31, 2015 USD ($) $ / shares	Dec. 15, 2015 USD ($) shares	Oct. 28, 2015 USD ($)	Oct. 07, 2015 $ / shares	Sep. 29, 2015 USD ($)	May 12, 2015 USD ($)	Nov. 09, 2014	Sep. 30, 2014 USD ($)	Apr. 01, 2014 USD ($)	Feb. 14, 2014 USD ($)	Nov. 06, 2013 USD ($)	Jun. 28, 2013 USD ($)	Apr. 18, 2013 USD ($)	Mar. 05, 2013 USD ($)	Nov. 02, 2012 USD ($)	Jan. 27, 2012 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																											$ 20,000
Premiums, Percentage Assumed to Net		1.00%
Assets Held-for-sale, Not Part of Disposal Group, Current, Other																	$ 1,800		$ 1,800
Investment Warrants, Exercise Price | $ / shares								$ 0.01
Repayment of notes receivable										$ 21,400									8,142		$ 54,653
Accounts Receivable, Net, Noncurrent	[1]																1,400		1,400					$ 0
Investment Owned, Balance, Shares | shares																																1.7
Investment Owned, at Cost																	6,600		6,600
Commitments and Contingencies																		[1]		[1]					[2]						$ 500					$ 8,500
Warrants and Rights Outstanding																	49		49					$ 78
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
LENSAR [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross														$ 40,000																		$ 42,000
Interest rate of note receivable (in Percent)														15.50%																						18.50%
Amount company has agreed to advance under agreement														$ 60,000
Alphaeon [Member]
Accounts Notes And Loans Receivable [Line Items]
Investment estimated fair value, per share | $ / shares																															$ 3.84
DirectFlow [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																										$ 1,000		$ 1,500		$ 1,500											$ 35,000
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down						$ 51,100
Proceeds from Sale of Other Assets			$ 700	$ 500	$ 7,000
Interest rate of note receivable (in Percent)																																					13.50%				15.50%
Amount company has agreed to advance under agreement												$ 15,000	$ 50,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares																											$ 0.01	$ 0.01
Paradigm Spine [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																													$ 54,700				$ 4,000							$ 50,000
Interest rate of note receivable (in Percent)																																								13.00%
Repayment of notes receivable							$ 57,500
Amount company has agreed to advance under agreement									$ 7,000								75,000
Maximum amount of additional funds, upon attainment of milestones																			25,000
Tranche 2 of note receivable																																	$ 3,000
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
Interest rate of note receivable (in Percent)																																							13.00%
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																							$ 0.40
Warrants and Rights Outstanding																	$ 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
Amount company has agreed to advance under agreement																						$ 8,700
Financing Receivable, Modifications, Post-Modification Recorded Investment															$ 44,100
Credit Agreement [Member] | LENSAR [Member]
Accounts Notes And Loans Receivable [Line Items]
Amount company has agreed to advance under agreement					$ 2,800
Initial Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment															33,700
Additional Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Commitments and Contingencies																																			$ 800
Additional Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																										$ 1,300
Additional Loan [Member] | LENSAR [Member]
Accounts Notes And Loans Receivable [Line Items]
Amount company has agreed to advance under agreement														$ 20,000
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, Pre-Modification Recorded Investment															1,300
Forbearance principal and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment															$ 9,100
Tranche three [Member] | DirectFlow [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																$ 5,000

[1] unaudited

[2] Note 1