Fair Value Measurements (Schedule of Fair Value of Assets and Liabilities not Subject to Fair Value Recognition) (Detail) (USD $)	3 Months Ended													1 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Series 2012 Notes [Member]	Dec. 31, 2012 Series 2012 Notes [Member]	Sep. 30, 2013 May 2015 Notes [Member]	Dec. 31, 2012 May 2015 Notes [Member]	Sep. 30, 2013 February 2015 Notes [Member]	Dec. 31, 2012 February 2015 Notes [Member]	Sep. 30, 2013 Wellstat Note Receivable [Member]	Dec. 31, 2012 Wellstat Note Receivable [Member]	Dec. 31, 2012 Merus Labs Note Receivable [Member]	Sep. 30, 2013 AxoGen Note Receivable [Member]	Dec. 31, 2012 AxoGen Note Receivable [Member]	Apr. 30, 2013 Avinger Note Receivable [Member]	Sep. 30, 2013 Avinger Note Receivable [Member]	Sep. 30, 2013 Fair Value Level 2 [Member]	Dec. 31, 2012 Fair Value Level 2 [Member]	Sep. 30, 2013 Fair Value Level 2 [Member] Series 2012 Notes [Member]	Dec. 31, 2012 Fair Value Level 2 [Member] Series 2012 Notes [Member]	Sep. 30, 2013 Fair Value Level 2 [Member] May 2015 Notes [Member]	Dec. 31, 2012 Fair Value Level 2 [Member] May 2015 Notes [Member]	Sep. 30, 2013 Fair Value Level 2 [Member] February 2015 Notes [Member]	Dec. 31, 2012 Fair Value Level 2 [Member] February 2015 Notes [Member]	Dec. 31, 2012 Fair Value Level 2 [Member] Merus Labs Note Receivable [Member]	Sep. 30, 2013 Fair Value Level 3 [Member]	Dec. 31, 2012 Fair Value Level 3 [Member]	Sep. 30, 2013 Fair Value Level 3 [Member] Wellstat Note Receivable [Member]	Dec. 31, 2012 Fair Value Level 3 [Member] Wellstat Note Receivable [Member]	Sep. 30, 2013 Fair Value Level 3 [Member] AxoGen Note Receivable [Member]	Dec. 31, 2012 Fair Value Level 3 [Member] AxoGen Note Receivable [Member]	Sep. 30, 2013 Fair Value Level 3 [Member] Avinger Note Receivable [Member]
Fair Value by Balance Sheet Grouping [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset												$ 1,000,000	$ 600,000
Assets
Notes receivable, Carrying Value	90,815,000	93,208,000							45,269,000	41,098,000	30,000,000	25,404,000	22,110,000		20,142,000
Notes receivable, Fair Value																	30,000,000							30,000,000	90,815,000	63,208,000	45,269,000	41,098,000	25,404,000	22,110,000	20,142,000
Fair value inputs, discount rate (in Percent)	35.00%													18.50%
Liabilities:
Notes Payble, Carrying Value	318,081,000	309,952,000	171,066,000	165,528,000	147,015,000	143,433,000		991,000
Notes payable, Fair Value																$ 457,122,000	$ 410,487,000	$ 258,984,000	$ 227,187,000	$ 198,138,000	$ 182,031,000		$ 1,269,000