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Employee Benefit Plans - Composition of Pension Plan Assets by Fair Value Level (Detail) - Defined Benefit Pension Plans - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | $ 46,313 | $ 40,626 | $ 44,222
United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 33,867 | 30,122 |
U.K. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 12,446 | 10,504 |
Equities | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 13,439 | 11,353 |
Fixed Income | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 16,290 | 13,856 |
Cash and Other | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 4,138 | 3,250 |
CMRT | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total |  | 1,663 |
Other | U.K. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 12,446 | 10,504 |
Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 35,722 | 30,130 |
Level 1 | Equities | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 3,789 | 3,423 |
Level 1 | Fixed Income | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 16,290 | 13,856 |
Level 1 | Cash and Other | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 3,197 | 2,347 |
Level 1 | Other | U.K. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 12,446 | 10,504 |
Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 439 | 1,663 |
Level 3 | Equities | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 439 |  |
Level 3 | CMRT | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total |  | 1,663 |
Assets Measured at NAV |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 10,152 | 8,833 |
Assets Measured at NAV | Equities | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | 9,211 | 7,930 |
Assets Measured at NAV | Cash and Other | United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | $ 941 | $ 903 |

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