VPT LOANS - Additional Information (Detail)		3 Months Ended		9 Months Ended
	Jul. 31, 2015 USD ($)	Dec. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) installment	Jul. 01, 2016 USD ($)	Apr. 30, 2017	Mar. 31, 2017 USD ($)	May 31, 2015 USD ($) installment	Jun. 30, 2014 USD ($)	Sep. 30, 2011 USD ($)
Long term notes receivable and available for sale securities [Line Items]
Commitment			$ 95,300,000	$ 68,500,000
Payments				18,200,000	$ 10,300,000
Available-for-sale securities:			95,300,000	68,500,000
Allowance			24,200,000	59,400,000
DRTC loans
Long term notes receivable and available for sale securities [Line Items]
Commitment			0	8,000,000
Original CPTC loans
Long term notes receivable and available for sale securities [Line Items]
Commitment		$ 98,100,000	95,300,000	60,500,000
Impairment charges		38,300,000
Available-for-sale securities:		60,000,000
NYPC loan
Long term notes receivable and available for sale securities [Line Items]
Accounts receivable from CPTC, includes unbilled accounts receivable			17,400,000	8,500,000
MPTC loans
Long term notes receivable and available for sale securities [Line Items]
Accounts receivable from CPTC, includes unbilled accounts receivable			9,200,000	$ 7,500,000
Commitment								$ 22,800,000
C P T C
Long term notes receivable and available for sale securities [Line Items]
Accounts receivable from CPTC, includes unbilled accounts receivable			32,600,000
Additional financing							$ 16,000,000
Interest rate				9.00%
CPTC loan facility, amortization period over which monthly payments are calculated after January 1, 2015 (in years)				15 years
Allowance		34,200,000
C P T C | Tranche C Loans
Long term notes receivable and available for sale securities [Line Items]
CPTC loan facility, Varian's maximum loan commitment				$ 9,700,000
C P T C | London Interbank Offered Rate (LIBOR)
Long term notes receivable and available for sale securities [Line Items]
CPTC loan facility, interest rate margin (as a percent)				7.00%
CPTC loan facility, minimum interest rate (as a percent)				9.00%
Available-for-sale Securities | C P T C | Tranche A loan
Long term notes receivable and available for sale securities [Line Items]
Maximum borrowing capacity										$ 165,300,000
Varian Medical Systems, Inc. | C P T C
Long term notes receivable and available for sale securities [Line Items]
Additional financing							$ 7,300,000
Varian Medical Systems, Inc. | C P T C | Tranche C Loans
Long term notes receivable and available for sale securities [Line Items]
CPTC loan facility, Varian's maximum loan commitment				$ 4,400,000
Varian Medical Systems, Inc. | Available-for-sale Securities | C P T C | Tranche A loan
Long term notes receivable and available for sale securities [Line Items]
CPTC loan facility, Varian's maximum loan commitment									$ 70,300,000	$ 115,300,000
Sale of portion of outstanding loan									38,100,000
Varian Medical Systems, Inc. | Available-for-sale Securities | C P T C | Tranche B loan
Long term notes receivable and available for sale securities [Line Items]
CPTC loan facility, Varian's maximum loan commitment									10,000,000
J P Morgan Chase Bank | Available-for-sale Securities | C P T C | Tranche A loan
Long term notes receivable and available for sale securities [Line Items]
Sale of portion of loan commitment									$ 45,000,000
Subordinated Bond | Proton International | DRTC loans
Long term notes receivable and available for sale securities [Line Items]
Interest rate (as a percent)						8.50%
Long-term				3,000,000
Subordinated Bond | Proton International | Public Finance Authority | DRTC loans
Long term notes receivable and available for sale securities [Line Items]
Notes receivable				3,000,000
Loans Receivable
Long term notes receivable and available for sale securities [Line Items]
Long-term			59,200,000	82,700,000
Loans Receivable | Proton International
Long term notes receivable and available for sale securities [Line Items]
Long-term			0	3,000,000
Loans Receivable | NYPC loan
Long term notes receivable and available for sale securities [Line Items]
Maximum lending commitment	$ 91,500,000
Long-term			18,500,000	$ 18,500,000
Loans Receivable | MPTC loans
Long term notes receivable and available for sale securities [Line Items]
Interest rate (as a percent)				12.00%
Maximum lending commitment								$ 35,000,000
Number of funding payments | installment				2
Number of annual payments | installment								3
Long-term			40,700,000	$ 56,100,000
Loans Receivable | Reclassification From Long-Term Notes Receivable | MPTC loans
Long term notes receivable and available for sale securities [Line Items]
Interest rate (as a percent)				15.00%
Deferral				$ 25,000,000
Long-term				21,100,000
Senior First Lien Loan | NYPC loan
Long term notes receivable and available for sale securities [Line Items]
Interest rate (as a percent)	9.00%
Maximum lending commitment	$ 73,000,000
Term (in years)	6 years
Senior Subordinated Loans | NYPC loan
Long term notes receivable and available for sale securities [Line Items]
Interest rate (as a percent)	13.50%
Maximum lending commitment	$ 18,500,000
Term (in years)	6 years 6 months
Roll Over Loan | MPTC loans
Long term notes receivable and available for sale securities [Line Items]
Notes receivable								$ 10,000,000.0
Commitment								12,200,000
Accrued interest								$ 2,200,000
Notes Receivable
Long term notes receivable and available for sale securities [Line Items]
Notes receivable			65,000,000	82,600,000
Long-term			59,200,000	$ 77,600,000
Notes Receivable | MPTC loans
Long term notes receivable and available for sale securities [Line Items]
Payments		$ 11,400,000	$ 11,400,000