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Summary of significant accounting policies.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount of the cumulative effect on retained earnings net of related income tax effect.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit.

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Significant Accounting Policies and Recently Issued Accounting Standards - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) Segment	Mar. 31, 2018 USD ($)	Dec. 31, 2017	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Expense on impairment of real estate assets	$ 0	$ 0
Insurance settlements receivable	11,000,000				$ 13,000,000
Income tax provision (benefits)	$ 5,000,000	$ (1,000,000)
Corporate income tax rate	21.00%	21.00%	35.00%
REIT dividends qualified business income deduction	20.00%
Federal deposit insurance corporation limit	$ 250,000
Number of reportable business segment \| Segment	1
Number of operating segments \| Segment	1
Right of use assets	$ 27,000,000
Lease liabilities	27,000,000
Retained earnings	1,000,000	$ (15,000,000)
Topic 842 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right of use assets				$ 27,000,000
Lease liabilities				$ 27,000,000
Retained earnings	1,000,000
Accounting Standards Update 2014-09 [Member] \| Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Summary Of Significant Accounting Policies [Line Items]
Decrease in retained earnings						$ (15,000,000)
REIT [Member]
Summary Of Significant Accounting Policies [Line Items]
Income tax provision (benefits)	$ 0