Transactions with Affiliates - Additional Information (Detail)		3 Months Ended
	Jul. 01, 2012 $ / mo	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jul. 02, 2012 ft² $ / ft²
Related Party Transaction [Line Items]
Description of management fee		In exchange for services provided, our Manager receives a management fee, paid monthly in arrears, in an amount equal to one-twelfth of 1.20% of our Equity (as defined in the Management Agreement).
Annual management fee as a percent of equity		1.20%
Number of days prior notice of non-renewal of the Management Agreement		180 days
Termination fees description		We are required to provide 180-days' prior notice of non-renewal of the Management Agreement and must pay a termination fee on the last day of any automatic renewal term equal to three times the average annual management fee earned by our Manager during the prior 24-month period immediately preceding the most recently completed month prior to the effective date of termination.
Sublease agreement, square feet leased | ft²				7,300
Rent paid for leased office space per square foot | $ / ft²				69.42
Sublease with PIA, expiration date	Jun. 30, 2022
New sublease agreement, base monthly rent | $ / mo	42,231.54
Sublease agreement, base monthly rent percentage increase starting July 1, 2017	3.00%
Rent		$ 139,000	$ 139,000
Fees paid for administrative services		Under our administrative services agreement with PIA, it provides administrative services and equipment to us including human resources, operational support and information technology, and we pay an annual fee of 5 basis points on the first $225 million of stockholders' equity and 2.25 basis points thereafter (paid quarterly in arrears) for those services. The administrative services agreement had an initial term of one year and renews for successive one-year terms thereafter unless either party gives notice of termination no less than 30 days before the expiration of the then-current annual term.
Basis points on equity for the annual fee		5 basis points on the first $225 million of stockholders' equity and 2.25 basis points thereafter (paid quarterly in arrears) for those services.
Stockholders equity amount used to calculate administrative service fees		$ 225,000,000
Prior written notice to terminate administrative agreement		30 days
Administrative service fees		$ 49,000	$ 39,000
First $225 million of Stockholders' Equity
Related Party Transaction [Line Items]
Basis points on equity for the annual fee		0.05%
Above $225 million of Stockholders' Equity
Related Party Transaction [Line Items]
Basis points on equity for the annual fee		0.0225%
Mr. Lloyd McAdams
Related Party Transaction [Line Items]
Outstanding membership interests		47.40%
Mr. Joseph E. McAdams
Related Party Transaction [Line Items]
Outstanding membership interests		47.40%
Mr. Brett Roth
Related Party Transaction [Line Items]
Change in Control and Arbitration Agreements, description		Under these agreements, in the event that a change in control occurs, each of these persons will receive a lump sum payment equal to (i) 12 months annual base salary in effect on December 31, 2011, plus (ii) the average annual incentive compensation received for the two complete fiscal years prior December 31, 2011, plus (iii) the average annual bonus received for the two complete fiscal years prior to December 31, 2011, as well as other benefits. For one of the Senior Vice Presidents and Portfolio Managers of our Manager, in the event that a change in control occurs, in addition to other benefits, he will receive a lump sum payment equal to (i) 12 months of the annual base salary (in effect on September 18, 2014) paid by our Manager plus (ii) $350,000.
Additional payment for change in control and arbitration agreements		$ 350,000
Ms. Heather U. Baines
Related Party Transaction [Line Items]
Outstanding membership interests		5.20%