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Derivative Financial Instruments - Additional Information (Detail) - USD ($) |  |  | 3 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Nov. 17, 2017 | Jun. 24, 2016 | Mar. 31, 2018 | Mar. 31, 2019 | Jan. 04, 2018 | Dec. 31, 2017 | Apr. 17, 2017
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount |  |  | $ 250,000,000 |  |  | $ 250,000,000 |
Derivative, strike rate for the interest rate swap contract |  | 1.145% |  |  |  |  | 1.1325%
Realized gains on interest rate hedges reclassified to earnings |  |  | 174,000 |  |  |  |
Unsecured Term Loan |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Secured credit facility borrowing capacity | $ 100,000,000 |  |  |  |  |  |
Cash Flow Hedge |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount |  |  | 250,000,000 |  |  | 200,000,000 |
Freestanding Derivatives | Other Income (Expense) |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Recognition of hedge ineffectiveness |  |  | 52,000 |  |  |  |
Interest Rate Swap |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount |  | $ 150,000 |  |  |  |  |
Derivative, maturity date |  | Jun. 17, 2021 |  |  |  |  |
Recognition of hedge ineffectiveness |  |  | 0 |  |  |  |
Interest Rate Swap | Cash Flow Hedge |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount |  |  | 150,000,000 |  |  | 150,000,000 |
Interest Rate Collar | Cash Flow Hedge |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount | $ 100,000,000 |  | $ 100,000,000 |  |  | 50,000,000 |
Derivative, maturity date | Nov. 17, 2024 |  |  |  |  |  |
Interest rate cap strike rate | 2.00% |  |  |  |  |  |
Floor interest rate | 1.25% |  |  |  |  |  |
Interest Rate Collar | Cash Flow Hedge | Designated |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount | $ 50,000,000 |  |  |  |  |  |
Interest Rate Collar | Freestanding Derivatives |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount | $ 50,000,000 |  |  |  |  | $ 50,000,000 |
Interest Rate Collar | Freestanding Derivatives | Designated |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Derivative, notional amount |  |  |  |  | $ 50,000,000 |  |
Interest Rate Swaps and Caps | Cash Flow Hedge | Scenario, Forecast |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Reclassified out of accumulated other comprehensive income to earnings, amount |  |  |  | $ 1,608,000 |  |  |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Interest rate cash flow hedge gain loss reclassified to earnings net of mark to market. + References No definition available. + Details
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- Definition Cap rate on an interest rate derivative such as an interest rate cap or collar. If market rates exceed the cap rate, a payment or receipt is triggered on the contract. + References No definition available. + Details
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- Definition Floor rate on an interest rate derivative such as an interest rate floor or collar. If market rates falls below the floor rate, a payment or receipt is triggered on the contract. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959 + Details
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- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
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- Definition The net gain (loss) during the reporting period due to ineffectiveness in interest rate cash flow hedges. Recognized in earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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