Notes Receivable and Other Long-term Receivables (Narrative) (Detail)												1 Months Ended					3 Months Ended					58 Months Ended
	Dec. 15, 2015 USD ($) shares	Oct. 27, 2015 USD ($)	Sep. 22, 2015 USD ($)	Sep. 14, 2015 USD ($)	Jun. 26, 2015 USD ($) $ / shares shares	Feb. 23, 2015 USD ($)	Nov. 14, 2014 USD ($)	Nov. 10, 2014 USD ($)	Nov. 05, 2013 USD ($)	Oct. 03, 2013 USD ($)	Aug. 15, 2013 USD ($)	Apr. 30, 2013 USD ($)	Feb. 28, 2013 USD ($)	Jan. 31, 2013 USD ($)	Oct. 31, 2012 USD ($)	Mar. 31, 2012 USD ($)	Mar. 31, 2016 USD ($) shares		Dec. 31, 2015 USD ($) $ / shares		Mar. 31, 2015 USD ($)	Apr. 30, 2018	Mar. 24, 2016 $ / shares shares	Dec. 01, 2015 USD ($)	Nov. 12, 2015 shares	Oct. 28, 2015 USD ($)	Oct. 07, 2015 USD ($) $ / shares	Sep. 29, 2015 USD ($)	Sep. 15, 2015 $ / shares shares	May. 12, 2015 USD ($)	Dec. 12, 2014 USD ($) $ / shares shares	Nov. 09, 2014	Apr. 01, 2014 USD ($)	Feb. 14, 2014 USD ($)	Feb. 06, 2014 $ / shares	Nov. 06, 2013 USD ($)	Aug. 14, 2013 USD ($) $ / shares shares	Jun. 28, 2013 USD ($)	Apr. 18, 2013 USD ($)	Mar. 05, 2013 USD ($)	Nov. 02, 2012 USD ($)	Aug. 31, 2012 USD ($)	Jan. 27, 2012 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																							$ 20,000,000
Repayment of notes receivable			$ 21,400,000
Investment Owned, Balance, Shares | shares	1,700,000
Share Price | $ / shares																																			$ 7.97
Equity investment, shares sold (shares) | shares																							50,000		149,650				200,000
Price per share of investment sold | $ / shares																							$ 5.44						$ 5.46
Marketable Securities, Realized Gain (Loss)																	$ 136,000
Proceeds from Sale of Available-for-sale Securities				$ 1,900,000
Proceeds from Sale of Available-for-sale Securities, Equity																	273,000				$ 0
Unrealized Gain (Loss) on Investments																	$ 418,000		$ 435,000
Commitments and Contingencies																		[1]		[2]										$ 8,500,000
Warrants and Rights Outstanding																	$ 1,099,000		$ 984,000
Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																	53,900,000
Financing receivable, modification, cost as a component of interest and other income, net											$ 2,500,000
Financing Receivable, Net																	50,200,000
Asset Management Costs																	15,200,000
Note receivable, amount legally owed																	$ 108,400,000
Interest rate of note receivable (in Percent)											5.00%
AxoGen [Member]
Accounts Notes And Loans Receivable [Line Items]
Repayment of notes receivable							$ 30,300,000
Investment Owned, Balance, Shares | shares																															643,382						1,166,666
Share Price | $ / shares																															$ 2.72						$ 3.00
Investment Owned, at Cost																															$ 1,700,000						$ 3,500,000
Price per share of investment sold | $ / shares																															$ 3.03
Equity investment, shares held (shares) | shares																	243,732
Proceeds from Sale of Available-for-sale Securities, Equity						$ 3,500,000
Investment Owned, at Fair Value																	$ 1,300,000
Unrealized Gain (Loss) on Investments																	600,000
Avinger [Member]
Accounts Notes And Loans Receivable [Line Items]
Repayment of notes receivable			$ 21,400,000
LENSAR [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross	$ 42,000,000									$ 40,000,000
Interest rate of note receivable (in Percent)										15.50%																				18.50%
Gain (Loss) on Sale of Notes Receivable	4,000,000
Other General and Administrative Expense	3,000,000
Amount company has agreed to advance under agreement										$ 60,000,000
Alphaeon [Member]
Accounts Notes And Loans Receivable [Line Items]
Investment estimated fair value, per share | $ / shares																			$ 3.84
Cost Method Investments, Original Cost	6,600,000
DirectFlow [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																				$ 35,000,000
Interest rate of note receivable (in Percent)																																13.50%				15.50%
Amount company has agreed to advance under agreement								$ 15,000,000	$ 50,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares					$ 0.01
Warrants and Rights Outstanding																	400,000
Paradigm Spine [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																		$ 50,000,000
Interest rate of note receivable (in Percent)																																		13.00%
Amount company has agreed to advance under agreement		$ 7,000,000															75,000,000
Maximum amount of additional funds, upon attainment of milestones																	25,000,000
Tranche 1 of note receivable																										$ 4,000,000
Tranche 2 of note receivable																										$ 3,000,000
Hyperion [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																											$ 2,300,000
Number of payments to be received																																											2
Periodic contractual payments																																								$ 1,200,000
First minimum payment																																								$ 1,200,000
kaleo Note Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																	$ 150,000,000
Interest rate of note receivable (in Percent)																																	13.00%
Note receivable payment received																								$ 9,500,000
Interest reserve balance																																	$ 20,000,000
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					$ 40,000,000
Tranche 1 of note receivable					20,000,000																						$ 20,000,000
Tranche 2 of note receivable					$ 20,000,000																						$ 20,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares					4,400,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares					$ 0.45																						$ 0.40
Warrants and Rights Outstanding																	700,000
Notes Receivable [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																$ 7,500,000																										$ 10,000,000
Term of receivable (in Duration)																2 years
Interest rate of note receivable (in Percent)																10.00%																										12.00%
Notes Receivable [Member] | Avinger [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																							$ 20,000,000
Interest rate of note receivable (in Percent)																																							12.00%
Amount company has agreed to advance under agreement												$ 40,000,000
Credit Agreement [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																									$ 40,000,000
Credit agreement, stated interest rate (in Percent)																																									5.00%
Proceeds received under remedies available for borrower's breach of terms credit agreement														$ 8,100,000
Amount company has agreed to advance under agreement													$ 7,900,000				$ 8,700,000
Financing Receivable, Modifications, Post-Modification Recorded Investment											$ 44,100,000
Forbearance period under terms of credit agreement (in Duration)													120 days
Initial Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment											33,700,000
Additional Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Commitments and Contingencies																												$ 800,000		$ 500,000
Additional Loan [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																						$ 1,300,000
Additional Loan [Member] | LENSAR [Member]
Accounts Notes And Loans Receivable [Line Items]
Amount company has agreed to advance under agreement										$ 20,000,000
Royalty Agreement [Member] | AxoGen [Member]
Accounts Notes And Loans Receivable [Line Items]
Term of receivable (in Duration)															8 years
Royalty rate on AxoGen net revenues (in percent)															9.95%
Guaranteed quarterly minimum payment-low															$ 1,300,000
Guaranteed quarterly minimum payment-high															$ 2,500,000
Term of royalty agreement (in Duration)															8 years
Total consideration paid to AxoGen for the royalty rights															$ 20,800,000
Initial interim funding for royalty rights															$ 1,800,000
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											1,300,000
Forbearance principal and interest [Member] | Wellstat Diagnostics [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment											$ 9,100,000
Tranche two [Member] | DirectFlow [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross																																				$ 15,000,000
Tranche three [Member] | DirectFlow [Member]
Accounts Notes And Loans Receivable [Line Items]
Financing receivable, gross	$ 5,000,000

[1] unaudited

[2] Note 1