BORROWINGS - Additional Information (Detail) - 9 months ended Jun. 30, 2017	JPY (¥)	USD ($)
Amended 2013 Credit Facility | 2013 Revolving Credit Facility
Line Of Credit Facility [Line Items]
Credit facility term (in years)	5 years
Loan facility, maximum borrowing capacity		$ 500,000,000
Amended 2013 Credit Facility | 2013 Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Expiration period (in months)	30 days
Amended 2013 Credit Facility | 2013 Revolving Credit Facility | Letter of Credit
Line Of Credit Facility [Line Items]
Loan facility, maximum borrowing capacity		50,000,000
Amended 2013 Credit Facility | 2013 Revolving Credit Facility | Swing Line Loans
Line Of Credit Facility [Line Items]
Loan facility, maximum borrowing capacity		25,000,000
Amended 2013 Credit Facility | 2013 Term Loan Facility
Line Of Credit Facility [Line Items]
Credit facility term (in years)	5 years
Loan facility, maximum borrowing capacity		500,000,000
Amended 2013 Credit Facility | Eurodollar | 2013 Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	1.125%
Amended 2013 Credit Facility | Eurodollar | 2013 Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	1.375%
Amended 2013 Credit Facility | Eurodollar | 2013 Term Loan Facility | Minimum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.875%
Amended 2013 Credit Facility | Eurodollar | 2013 Term Loan Facility | Maximum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	1.125%
Amended 2013 Credit Facility | Federal Funds Effective Swap Rate | 2013 Revolving Credit Facility
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.50%
Amended 2013 Credit Facility | Federal Funds Effective Swap Rate | 2013 Term Loan Facility
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.50%
Amended 2013 Credit Facility | Eurodollar1 | 2013 Revolving Credit Facility
Line Of Credit Facility [Line Items]
Percentage added to Eurodollar base rate before margin (as a percent)	1.00%
Amended 2013 Credit Facility | Eurodollar1 | 2013 Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.125%
Amended 2013 Credit Facility | Eurodollar1 | 2013 Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.375%
Amended 2013 Credit Facility | Eurodollar1 | 2013 Term Loan Facility
Line Of Credit Facility [Line Items]
Percentage added to Eurodollar base rate before margin (as a percent)	1.00%
Amended 2013 Credit Facility | Eurodollar1 | 2013 Term Loan Facility | Maximum
Line Of Credit Facility [Line Items]
Line of credit, interest rate (as a percent)	0.125%
2013 Credit Facility | 2013 Revolving Credit Facility
Line Of Credit Facility [Line Items]
Additional maximum commitment amount		100,000,000
2013 Credit Facility | 2013 Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Commitment fee	0.125%
2013 Credit Facility | 2013 Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Commitment fee	0.20%
2013 Credit Facility | 2013 Term Loan Facility
Line Of Credit Facility [Line Items]
Additional maximum commitment amount		$ 100,000,000
Sumitomo Credit Facility
Line Of Credit Facility [Line Items]
Loan facility, maximum borrowing capacity | ¥	¥ 3,000,000,000
Line of credit, interest rate (as a percent)	0.50%