Disclosure of Fair Value of Financial Instruments - Additional Information (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)	Jun. 30, 2018	Mar. 31, 2018
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets measured at fair value on a recurring basis	$ 48,049,000	$ 69,014,000
Fair Value, Inputs, Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets measured at fair value on a recurring basis	0	0
Liabilities measured at fair value on a recurring basis	$ 0	$ 0