Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Liabilities:
Liquidating distributions payable	$ 343,874	$ 1,785
Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	434,735	503,262
Liabilities:
Liquidating distributions payable	343,874	1,785
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | Money Market Funds [Member]
Assets:
Total Assets	497	34
Fair Value, Measurements, Recurring [Member] | Marketable Securities [Member] | U.S. Treasury Bills [Member]
Assets:
Total Assets	434,238	503,228
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Total Assets	497	34
Liabilities:
Liquidating distributions payable	343,874	1,785
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Cash Equivalents [Member] | Money Market Funds [Member]
Assets:
Total Assets	497	34
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets:
Total Assets	434,238	503,228
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Marketable Securities [Member] | U.S. Treasury Bills [Member]
Assets:
Total Assets	$ 434,238	$ 503,228