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Employee Benefit Plans - Summary of Pension Plan Assets (Detail) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | --- | ---
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | $ 52,250 | $ 57,746 |
Total Pension Plan Assets, excluding investments measured at net asset value |  | 46,692 | 50,498 |
Investments measured at net asset value | [1] | 5,558 | 7,248 |
Investments in equity securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 20,499 | 24,382 |
Investments in equity securities | Us Large Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 3,399 | 4,245 |
Investments in equity securities | Us Mid Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 1,478 | 1,775 |
Investments in equity securities | United States Equity Small Cap |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 670 | 918 |
Investments in equity securities | International All Cap Equity |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [3] | 9,226 | 11,916 |
Investments in equity securities | Alternative Strategies |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [4] | 5,726 | 5,528 |
Debt securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 21,448 | 21,226 |
Debt securities | Fixed Income |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 18,630 | 18,454 |
Debt securities | High Yield Asset Backed Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 2,818 | 2,772 |
Other |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 4,745 | 4,890 |
Other | Commodities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [6] | 1,902 | 2,154 |
Other | Real Estate |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [7] | 2,216 | 2,300 |
Other | Guaranteed deposit |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [8] | 627 | 436 |
Quoted Prices in Active Markets (Level 1) |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 46,065 | 50,062 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 20,499 | 24,382 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Us Large Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 3,399 | 4,245 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Us Mid Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 1,478 | 1,775 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | United States Equity Small Cap |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 670 | 918 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | International All Cap Equity |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [3] | 9,226 | 11,916 |
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Alternative Strategies |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [4] | 5,726 | 5,528 |
Quoted Prices in Active Markets (Level 1) | Debt securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 21,448 | 21,226 |
Quoted Prices in Active Markets (Level 1) | Debt securities | Fixed Income |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 18,630 | 18,454 |
Quoted Prices in Active Markets (Level 1) | Debt securities | High Yield Asset Backed Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 2,818 | 2,772 |
Quoted Prices in Active Markets (Level 1) | Other |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 4,118 | 4,454 |
Quoted Prices in Active Markets (Level 1) | Other | Commodities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [6] | 1,902 | 2,154 |
Quoted Prices in Active Markets (Level 1) | Other | Real Estate |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [7] | 2,216 | 2,300 |
Quoted Prices in Active Markets (Level 1) | Other | Guaranteed deposit |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [8] | 0 | 0 |
Significant Other Observable Inputs (Level 2) |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Us Large Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Us Mid Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities | United States Equity Small Cap |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities | International All Cap Equity |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [3] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Alternative Strategies |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [4] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Debt securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Debt securities | Fixed Income |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Debt securities | High Yield Asset Backed Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Other |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Other | Commodities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [6] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Other | Real Estate |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [7] | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Other | Guaranteed deposit |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [8] | 0 | 0 |
Significant Unobservable Inputs (Level 3) |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 627 | 436 | $ 498
Significant Unobservable Inputs (Level 3) | Investments in equity securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Us Large Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Us Mid Cap Equity Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Investments in equity securities | United States Equity Small Cap |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [2] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Investments in equity securities | International All Cap Equity |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [3] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Alternative Strategies |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [4] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Debt securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Debt securities | Fixed Income |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Debt securities | High Yield Asset Backed Securities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [5] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Other |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets |  | 627 | 436 |
Significant Unobservable Inputs (Level 3) | Other | Commodities |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [6] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Other | Real Estate |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [7] | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Other | Guaranteed deposit |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |
Total Pension Plan Assets | [8] | $ 627 | $ 436 |
[1] | Certain investments that were measured at net asset value per share have not been classified in the fair value hierarchy. These amounts are presented to reconcile to total pension plan assets.
[2] | Includes funds that invest primarily in United States common stocks.
[3] | Includes funds that invest primarily in foreign equities and emerging markets equities.
[4] | Includes funds that actively invest in both equity and debt securities, funds that sell short securities and funds that provide long-term capital appreciation. The funds may invest in debt securities below investment grade.
[5] | Includes funds that invest in investment grade and fixed income securities.
[6] | Includes funds that invest primarily in commodity-linked derivative instruments and fixed income securities.
[7] | Includes funds that invest primarily in real estate.
[8] | Includes investment in a group annuity product issued by an insurance company.

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