Income Taxes - Summary of Combined Activity and Taxable Activity (Detail) - TRS [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Before Income Taxes [Line Items]
Book income before income taxes	$ 1,872	$ 11,180	$ 9,953
Current	(430)	459	17
Deferred	0	0	0
Total income tax (benefit) expense	$ (430)	$ 459	$ 17

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Name:	us-gaap_DeferredIncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration